Galactic Rings Signposts of Secular Evolution in Disk Galaxies · Galactic Rings Signposts of Secular Evolution in Disk Galaxies 27th May, 2018 { 1st June, 2018 The University of

Galactic RingsSignposts of Secular Evolution in Disk Galaxies

27th May, 2018 – 1st June, 2018

The University of AlabamaBryant Conference Center240 Paul W. Bryant Drive

Tuscaloosa, AL 35401

Contents

Venue Map 1

Logistics 2Venue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Internet/Wifi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Conference Mobile App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Shuttle Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Program 3Sunday . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Monday . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Tuesday . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Wednesday . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Thursday . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Friday . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Organizing Committees and Sponsors 8SOC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8LOC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Sponsors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Abstracts 9

Session I - Overview of Galactic Rings9

Galactic Rings: Historical OverviewKenneth Charles Freeman . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Rings and Disk ResonancesJ. Alfonso L. Aguerri . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Session II - Structural Properties of Rings10

Galaxy Evolution and the Morphology of Galactic Disk RingsRon James Buta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Multi-component structural decompositions of barred and ringed galaxiesHeikki Salo, Eija Laurikainen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

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Galactic Rings: Signposts of Secular Evolution in Disk GalaxiesMay 27 - June 1, 2018 - The University of Alabama - Tuscaloosa AL

Inner and (Mostly) Outer Rings and the Structure of Galactic DisksPeter Erwin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

The intrinsic shape of galactic structures in ringed galaxiesJairo Mendez-Abreu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Session III - Dynamics of Ringed Galaxies12

A multi-aspect view of bars and of the structures they driveLia Athanassoula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Rings and manifolds in barred galaxies.Merce Romero-Gomez, Lia Athanassoula, J.J.Masdemont . . . . . . . . . . . 12

Time-dependent resonances in barred galaxies: Implications for ring structuresand secular evolutionDaniel Pfenniger, Kanak Saha, Yu-Ting Wu, Ron Taam . . . . . . . . . . . . 13

Session IV - Poster Session I14

Rings as the shutdown of radial transportJohn C. Forbes, Mark Krumholz, Andreas Burkert, Avishai Dekel . . . 14

Kinematics of the ionized gas of the active ring galaxy NGC 5728Isaura L. Fuentes-Carrera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Ring galaxies as gravitational probes of pure dark matter halosMarja K Seidel, Barry Madore, Melissa Jacquart, Michael Weisberg . 15

Forging Dark Rings - Radial Clearing of Dust near Resonance RingsWilliam C. Keel, Benne Holwerda, Sarah Bradford, Anna M. Davis,Chris Lintott . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Comparison of Corotation Resonance DeterminationsRonald James Buta, Xiaolei Zhang . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Making models of stellar halos to identify merger historiesShahram Talei, Jeremy Bailin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Session V - Multi-Wavelength Tracers of Star Formation I17

Star Formation and Stellar Populations in Disk RingsJohan Knapen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Multi-wavelength observations of galactic ringsFrancoise Combes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Rings in the KPAIR Herschel Survey of Galaxy PairsDonovan Louis Domingue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Current Star Formation Rates in Early-Type Disk Galaxies with Outer RingsIrina Petrovna Kostiuk, Olga Sil’chenko . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

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Session VI - Multi-Wavelength Tracers of Star Formation II18

Ultraviolet Rings in S0 galaxiesOlga K. Sil’chenko, Irina Proshina, Alexei Kniazev, Oleg Egorov . . . . 18

The TIMER Project: Time Inference with MUSE in Extragalactic RingsDimitri Gadotti and the TIMER team . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Rings and Rays: a Chandra View of NGC 3081Walter Peter Maksym, Martin Elvis, Pepi Fabbiano, M. Karovska,Alessandro Paggi, John Raymond, Guido Risaliti,Thaisa Storchi-Bergmann, Junfeng Wang . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Bars, rings, and signatures of secular evolution as seen in the S4G surveySimon Dıaz-Garcıa, Johan Knapen, Heikki Salo, Eija Laurikainen,Martn Herrera-Endoqui . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Session VII - Ringed and Barred Galaxies21

Inner Rings in Barred Galaxies as probes to unravel disk galaxy evolutionMarja Kristin Seidel, Dimitri A. Gadotti, Paula Coelho, CharlotteDonohoe-Keyes, Jesus Falcon-Barroso, Francesca Fragkoudi, BerndHusemann, Taehyun Kim, Ryan Leaman, Gigi Leung, Adriana deLorenzo-Caceres, Marie Martig, Inma Martinez-Valpuesta, JustusNeumann, Isabel Perez, Miguel Querejeta, Patricia Sanchez-Blazquez,Glenn van de Ven . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Feedback from nuclear rings: Caught in the act with ALMA & MUSE-TIMER dataFrancesca Fragkoudi, Ryan Leaman, Miguel Querejeta, Gigi Leung,Dimitri Gadotti . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

On the origin of nuclear rings in barred galaxiesMattia Carlo Sormani, Francesca Fragkoudi, Emanuele Sobacchi,Matthew Ridley . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Effects of Disk Mass and Gas Fraction on the Formation of Nuclear ringsWoo-Young Seo, Woong-Tae Kim, Phil Hopkins . . . . . . . . . . . . . . . . . . . . 23

Ansae in barred ringed galaxiesIvan Katkov, Alexei Kniazev, Olga Sil’chenko . . . . . . . . . . . . . . . . . . . . . . . 23

Unveiling the nature of barlens structures with TIMERIsabel Perez and the TIMER collaboration . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Session VIII - Poster Session II 24Barlenses in the CALIFA survey

Eija Irene Laurikainen, Heikki Salo, Jarkko Laine, Joachim Janz . . . . 24The Nature of Star Formation within Bars

Justus Neumann, Dimitri Gadotti, Lutz Wisotzki, Bernd Husemann,and CARS collaboration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

The Secular Origin of the Milky Way bulgeFrancesca Fragkoudi, Paola Di Matteo, Misha Haywood, MathiasSchultheis, Sergey Khoperskov, Ana Gomez, Francoise Combes . . . . . . 25

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2D metallicity gradients and how they depend on substructures in MaNGAgalaxiesAmy Michelle Jones, Preethi Nair, and the MaNGA team . . . . . . . . . . . 26

NGC 4622: A clear example of spiral density wave star formation in a ringgalaxyGene Gilbert Byrd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Arm structure, bars and rings in 3-armed spiral galaxiesColin Hancock, Bill Keel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

How do spiral arm contrasts relate to bars, disc breaks and other fundamentalgalaxy properties?Adrian Bittner, Dimitri A. Gadotti, Bruce G. Elmegreen, LiaAthanassoula, Debra M. Elmegreen, Albert Bosma, Juan-CarlosMunoz-Mateos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Session IX - Barred Galaxies Dynamics29

Collective Effects and Secular Dynamical Evolution of GalaxiesXiaolei Zhang, Ron Buta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Constraints on angular momentum changes for corotating starsKathryne J. Daniel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Annular kinematic segregation of galaxy disksJoan Font, John E. Beckman . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Bar pattern speed estimates using the Tremaine-Weinberg method in MaNGAgalaxiesLuis A Garma, Erik Aquino-Ortiz, Hector Hernandez-Toledo, Mari-ana Cano-Diaz, Octavio Valenzuela, Sebastian F. Sanchez . . . . . . . . . . 31

Session X - Properties of Barred Galaxies31

Spatially Resolved Metallicity Distributions in Barred and Unbarred Galaxies:Implications for Galaxy Evolution since z∼2Shardha Jogee, Kyle Kaplan, Lisa Kewley, Guillermo A. Blanc, andthe VENGA collaboration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

The Origin of Bars in Quenched Disk Galaxies: A MaNGA ViewAmelia K. Fraser-McKelvie, Alfonso Aragon-Salamanca, MichaelMerrifield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Determining the epoch of bar formationCharlotte Donohoe-Keyes, Phil James, Marie Martig and the TIMERCollaboration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Secular evolution driven by double-barred systems in the TIMER surveyAdriana de Lorenzo-Caceres, and the TIMER team . . . . . . . . . . . . . . . . . 33

Photometric Properties of Bars in Low Surface Brightness GalaxiesWesley Peters, Rachel Kuzio de Naray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

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Session XI - Spiral Structures in Disk Galaxies34

Formation and Evolution of Spiral Structure in Disk GalaxiesElena D’Onghia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

The properties and origins of spiral structure across the galaxy populationWilliam Clifford Keel, Steven Bamford, Ross Hart, and the GalaxyZoo team . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Study of stellar formation and evolution in spiral galactic disksCarmen Sanchez Gil, Emilio J. Alfaro Navarro, Enrique Perez, MiguelCervino, Joss Bland-Hawthorn, Heath Jones . . . . . . . . . . . . . . . . . . . . . . . . 35

A new technique to measure pattern speeds of spirals in MaNGATom Peterken, Michael Merrifield, Alfonso Aragon-Salamanca . . . . . . 36

Session XII - Collisional Ring Galaxies37

Accretion-generated rings: coplanar and non-coplanar structuresAlexei Moiseev . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

The Star-forming ISM in Collisional Ring GalaxiesJames Lloyd Higdon, Sarah J. U. Higdon, Richard J. Rand, SergioMartin Ruiz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

This Cartwheel’s on Fire: Gas Flows and Star Formation in Collisional RingGalaxiesFlorent Renaud . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Session XIII - Rings in Milky Way and Local Group Galaxies38

Understanding the nuclear ring and other gaseous features of the Milky WayJuntai Shen, Zhi Li, Ortwin Gerhard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Are the Near and Far 3 Kiloparsec Arms of the Milky Way Actually A GalacticRing?Robert Benjamin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

A Ring-like Stellar Overdensity Structure in the Large Magellanic CloudYumi Choi, David Nidever, Knut Olsen, Gurtina Besla, Robert Blum,Cliff Johnson, Dennis Zaritsky and the SMASH team . . . . . . . . . . . . . . . 39

Unravelling the Origin of the Monoceros Ring - Detailed abundances in theSouthern StructureThomas Bensby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Session XIV - Secular Processes in Disk Galaxies40

Spiral arms, the warp & the stream in M33 as a result of an interaction with M31Marcin Semczuk, Ewa L. Lokas, Jean-Baptiste Salomon, E. Athanas-soula, Elena D’Onghia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

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Black Hole Mass Scaling Relations for Spiral Galaxies Determined from PitchAngles and Multicomponent Structural DecompositionsBenjamin Lee Davis, Alister Graham, Marc Seigar, Ewan Cameron . 41

Black Hole Growth in Disk Galaxies Mediated by the Secular Evolution ofShort BarsMin Du, Victor P. Debattista, Juntai Shen, Luis C. Ho,Peter Erwin . 41

A combined photometric and kinematic recipe for evaluating the nature ofbulges using the CALIFA sampleJustus Neumann, L. Wisotzki, O. Choudhury, D. Gadotti, C.J.Walcher, J. Bland-Hawthorn, R. Garcia-Benito, R.M. Gonzales-Delgado, B. Husemann, R.A. Marino, I. Marquinez, S.F. Sanchez,B. Ziegler and CALIFA collaboration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

The Dust Forecast, Predicting the Dust Attenuation in Spiral Disk GalaxiesBenne Willem Holwerda, Bill Keel, and the Galaxy Zoo team . . . . . . . 43

Session XV - Rings and other Galaxy Structure in Simulations44

Ring galaxies in the nearby and distant UniverseFrederic Bournaud . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Warps, waves and rings in the stellar discs of Auriga cosmological simulationsFacundo Ariel Gomez, Simon D.M. White, Robert J.J. Grand, F.Marinacci, V.Springel, R. Pakmor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Galactic bars and galaxy interactions in the Illustris simulationNicolas Peschken . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Tidally induced bars in gas-rich dwarf galaxies orbiting the Milky WayGrzegorz Gajda, Ewa L. Lokas, Lia Athanassoula . . . . . . . . . . . . . . . . . . . 45

Bar formation in cosmological simulationsTommaso Zana, Massimo Dotti, Francesco Haardt, Pedro R. Capelo,Lucio Mayer, Silvia Bonoli . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Session XVI - Secular Structures in a Cosmological Context47

Galaxy Morphology from Galaxy ZooKaren L Masters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Redshift evolution of bars, rings and spiral armsPreethi Nair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Session XVII - Discussion and Concluding Remarks 47

Author Index 48

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Logistics

VenueRegistration and check-in will take place in ‘Sellers Lobby’ at the Bryant ConferenceCenter. All conference sessions will take place in ‘Sellers Auditorium’. Lunches willtake place in Rast A & B. Opening reception will be in Rast B.

Internet connectionWi-Fi Network : UA-BryantConfCtr-BryantMuseumWi-Fi Password: ∗Bryant#1913Eduroam is also available

Conference Mobile AppSearch and download “UA Conference Services” in your Apple or Google Play Store.Enter the Event ID: galacticUsername: your email (entered during abstract submission/registration)Password: galactic

Daily Shuttle Service

Hotel IndigoShuttle will leave from the hotel at 8:20 a.m. each day.Shuttle will leave from the BCC at 5:45 p.m. each day.

Hampton InnShuttle will leave from the hotel at 8:35 a.m. each day.Shuttle will leave from the BCC at 5:45 p.m. each day.

Airport Return Shuttle ServiceFriday, June 1stShuttle leaves BCC at 12:00 p.m.; Arrives at airport at 1:15 p.m.Shuttle leaves BCC at 2:00 p.m.; Arrives at airport at 3:15 p.m.

Saturday, June 2ndShuttle leaves Hotel Capstone at 8:00 a.m.; Arrives at airport at 9:15 a.m.Shuttle leaves Hotel Capstone at 2:00 p.m.; Arrives at airport at 4:15 p.m.

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ProgramSunday, May 27, 2018

5:00 - 7:00 p.m.: Opening Reception at Bryant Conference Center

Monday, May 28, 2018

8:00 a.m. - 9:00 a.m. Registration & Refreshments9:00 a.m. - 10:25 a.m. Session I: Observational and Theoretical Overviews of Rings

R. Buta & F. Combes Conference Introductions and LogisticsKen Freeman Galactic Rings: Historical OverviewJ. Alfonso L. Aguerri Rings and Disk Resonances10:25 a.m. - 10:55 a.m. Coffee Break10:55 a.m. - 12:30 p.m. Session II: Structural Properties of RingsRon Buta Galaxy Evolution and the Morphology of Galactic Disk RingsHeikki Salo Multicomponent Structural Decompositions of Barred and

Ringed GalaxiesPeter Erwin Inner and (Mostly) Outer Rings and the Structure of Galactic

DisksJairo Mendez-Abreu The Intrinsic shape of galactic structures in ringed galaxies12:30 p.m. - 2:00 p.m. Lunch Break

2:00 p.m. - 3:30 p.m. Session III: Dynamics of Ringed GalaxiesLia Athanassoula A multi-aspect view of bars and of the structures they driveMerce Romero-Gomez Rings and manifolds in barred galaxiesDaniel Pfenniger Time-dependent resonances in barred galaxies: Implications

for ring structures and secular evolution3:30 p.m. - 4:00 p.m. Coffee Break4:00 p.m. - 5:30 p.m. Session IV: Poster Session

5-minute lightning talksJohn Forbes Rings as the shutdown of radial transportRon Buta Comparison of Corotation Resonance DeterminationsMarja Seidel Ring galaxies as gravitational probes of pure dark matter ha-

losBill Keel Forging Dark Rings - Radial Clearing of Dust near Resonance

RingsIsaura Fuentes-Carrera Kinematics of the ionized gas of the active ring galaxy NGC

5728Shahram Talei Making models of stellar halos to identify merger histories

4:30 p.m. - 5:30 p.m. Poster Viewing6:00 p.m. Early Career Scientists Dinner – Surin Thai

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Tuesday, May 29, 2018

8:00 a.m. - 9:00 a.m. Registration & Refreshments9:00 a.m. - 10:30 a.m. Session V: Multi-Wavelength Tracers of Star Formation I

Johan Knapen Star Formation and Stellar Populations in Disk RingsFrancoise Combes Multi-wavelength Observations of Galactic RingsDonovan Domingue Rings in the KPAIR Herschel Survey of Galaxy PairsIrina Kostiuk Current Star-Formation Rates in Early-Type Disk Galaxies

with Outer Rings10:30 a.m. - 11:00 a.m. Coffee Break11:00 a.m. - 12:30 p.m. Session VI: Multi-Wavelength Tracers of Star Formation IIOlga Sil’chenko Ultraviolet Rings in S0 GalaxiesDimitri Gadotti The TIMER Project: Time Inference with MUSE in Extra-

galactic RingsWalter Maksym Rings and Rays: a Chandra View of NGC 3081Simon Dıaz-Garcıa Bars, rings, and signatures of secular evolution as seen in the

S4G survey12:30 p.m. - 2:00 p.m. Lunch Break

2:00 p.m. - 3:55 p.m. Session VII: Ringed and Barred GalaxiesMarja Seidel Inner Rings in Barred Galaxies as probes to unravel disk

galaxy evolutionFrancesca Fragkoudi Feedback from nuclear rings: Caught in the act with ALMA

and MUSE-TIMER dataMattia Sormani On the origin of nuclear rings in barred galaxiesWoo-Young Seo Effects of Disk Mass and Gas Fraction on the Formation of

Nuclear Rings.Ivan Katkov Ansae in barred ringed galaxiesIsabel Perez Unveiling the nature of barlens structures with TIMER

3:55 p.m. - 4:25 p.m. Coffee Break4:25 p.m. - 5:30 p.m. Session VIII: Poster Session

5-minute lightning talksEija Laurikainen Barlenses in the CALIFA surveyJustus Neumann The Nature of Star Formation within BarsFrancesca Fragkoudi The secular origin of the Milky Way bulgeAmy Jones 2D metallicity gradients and how they depend on substruc-

tures in MaNGA galaxiesGene Byrd NGC 4622: A clear example of spiral density wave star for-

mation in a ring galaxyColin Hancock Arm structure, bars and rings in 3-armed spiral galaxiesAdrian Bittner How do spiral arm contrasts relate to bars, disc breaks and

other fundamental galaxy properties?5:00 p.m. - 5:30 p.m. Poster Viewing

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Wednesday, May 30, 2018

8:00 a.m. - 9:00 a.m. Registration & Refreshments9:00 a.m. - 10:30 a.m. Session IX: Barred Galaxy Dynamics

Xiaolei Zhang Collective Effects and Secular Dynamical Evolution of GalaxiesKathryne Daniel Constraints on angular momentum changes for corotating starsJoan Font Annular kinematic segregation of galaxy disksLuis Garma Bar pattern speed estimates using the Tremaine-Weinberg

method in MaNGA galaxies10:30 a.m. - 11:00 a.m. Coffee Break10:55 a.m. - 12:30 p.m. Session X: Barred Galaxy PropertiesShardha Jogee Spatially Resolved Metallicity Distributions in Barred and Un-

barred Galaxies: Implications for Galaxy Evolution since z∼2Amelia The Origin of Bars in Quenched Disk Galaxies: A MaNGAFraser-McKelvie ViewCharlotte Determining the epoch of bar formationDonohoe-KeyesAdriana de Lorenzo-Caceres

Secular evolution driven by double-barred systems in theTIMER survey

Wesley Peters Photometric Properties of Bars in Low Surface BrightnessGalaxies

12:45 p.m. - 6:00 p.m. Excursion with boxed lunchesEnd of Day 3Dinner on own

12:45 p.m. - 2:00 p.m. Shuttle to Moundville ∼ 40 minute drive2:00 p.m. - 3:00 p.m. Picnic lunch – Indoor or outdoor at Moundville. Boxed

lunches need to be ordered on Monday at registration desk.Lunch cost is not included in registration.

3:00 p.m. - 5:00 p.m. Moundville grounds and museum tour with tour guides.Please wear comfortable shoes.

5:00 p.m. - 6:00 p.m. Shuttle returns participants to hotels.

For those not attending the Moundville excursion, a guided tour of the fossil collectionat the Alabama Museum of Natural History (AMNH) can be arranged between 2:00 -4:00 p.m.

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Thursday, May 31, 2018

8:00 a.m. - 9:00 a.m. Registration & Refreshments9:00 a.m. - 10:35 a.m. Session XI: Spiral Structures in Disk GalaxiesElena D’Onghia Formation and Evolution of Spiral Structure in Disk GalaxiesBill Keel, Steven Bam-ford

The properties and origins of spiral structure across the galaxypopulation

Carmen Sanchez Gil Study of stellar formation and evolution in spiral galactic disksTom Peterken A new technique to measure pattern speeds of spirals

in MaNGA10:35 a.m. - 11:05 a.m. Coffee Break11:05 a.m. - 12:30 p.m. Session XII: Collisional Ring GalaxiesAlexei Moiseev Accretion-generated rings: coplanar and non-coplanar struc-

turesJames Higdon The Star-forming ISM in Collisional Ring GalaxiesFlorent Renaud This Cartwheels on fire: gas flows and star formation in colli-

sional ring galaxies12:30 p.m. - 2:00 p.m. Lunch Break

2:00 p.m. - 3:30 p.m. Session XIII: Rings in Milky Way and Local Group GalaxiesJuntai Shen Understanding the nuclear ring and other gaseous features of

the Milky WayRobert Benjamin Are the Near and Far 3 Kiloparsec Arms of the Milky Way

Actually A Galactic Ring?Yumi Choi A Ring-like Stellar Overdensity Structure in the Large Magel-

lanic CloudThomas Bensby Unravelling the Origin of the Monoceros Ring - Detailed abun-

dances in the Southern Structure3:30 p.m. - 4:00 p.m. Coffee Break4:00 a.m. - 5:30 p.m. Session XIV: Secular Processes in Disk Galaxies

Marcin Semczuk Spiral arms, the warp and the stream in M33 as a result of aninteraction with M31

Benjamin Davis Black Hole Mass Scaling Relations for Spiral Galaxies Deter-mined from Pitch Angles and Multicomponent Structural De-compositions

Min Du Black Hole Growth in Disk Galaxies Mediated by the SecularEvolution of Short Bars

Justus Neumann A combined photometric & kinematic recipe for evaluating thenature of bulges using CALIFA.

Benne Holwerda The Dust Forecast; Predicting the Dust Attenuation in SpiralDisk Galaxies.

6:30 p.m. - 7:00 p.m. Refreshments at Alabama Museum of Natural History7:00 p.m. - 9:00 p.m. Conference Dinner at Alabama Museum of Natural History

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Friday, June 1, 2018

8:00 a.m. - 9:00 a.m. Registration & Refreshments9:00 a.m. - 10:50 a.m. Session XV: Rings and other Galaxy Structure in Simulations

Frederic Bournaud Ring galaxies in the nearby and distant UniverseFacundo Gomez Warps, waves and rings in the stellar discs of the Auriga cos-

mological simulationsNicolas Peschken Galactic bars and galaxy interactions in the Illustris simula-

tionGrzegorz Gajda Tidally induced bars in gas-rich dwarf galaxies orbiting the

MilkyTomasso Zana Bar formation in cosmological simulations10:50 a.m. - 11:15 a.m. Coffee Break11:15 a.m. - 12:20 p.m. Session XVI: Cosmological ContextKaren Masters Galaxy Morphology from Galaxy ZooPreethi Nair Redshift evolution of bars, rings and spiral arms12:20 p.m. - 12:45 p.m. Session XVII: Wrap-up

Discussion & Conference SummaryEnd of Conference

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Scientific Organizing Committee

Ronald Buta, The University of Alabama, US (co-chair)Francoise Combes, Observatoire de Paris, France (co-chair)Lia Athanassoula, Laboratoire d’Astrophysique de Marseille, FranceVictor Debattista, University of Central Lancashire, United KingdomPeter Erwin, Max-Planck-Institute for Extraterrestrial Physics, GermanyKenneth Freeman, The Australian National University, AustraliaDimitri Gadotti, European Southern Observatory, GermanyEnrica Iodice, INAF-Astronomical Observatory of Capodimonte, ItalyWoong-Tae Kim, Seoul National University, KoreaJohan Knapen, Instituto de Astrofsica de Canarias, SpainEija Laurikainen, University of Oulu, FinlandPreethi Nair, The University of Alabama, USJuntai Shen, Shanghai Astronomical Observatory, ChinaOlga Sil’chenko, Sternberg Astronomical Institute, Lomonosov MSU, Russia

Local Organizing Committee

Preethi Nair, The University of Alabama, US (co-chair)Ronald Buta, The University of Alabama, US (co-chair)Jeremy Bailin, The University of Alabama, USAmy Jones, The University of Alabama, USBill Keel, The University of Alabama, USLauren Lewis, Bryant Conference Center, USSea Talantis, Bryant Conference Center, US

Sponsors

The Dept. of Physics & Astronomy, The University of AlabamaThe College of Arts & Sciences, The University of AlabamaThe College of Continuing Studies, The University of AlabamaTuscaloosa Tourism and Sports Commission

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Abstracts

Monday, May 28, 2018

Session I - Overview of Galactic Rings

Galactic Rings: Historical Overview 28May09:0540 min

Kenneth Charles Freeman

Research School of Astronomy & Astrophysics, The Australian National University

The various families of galactic rings provide insights into a wide range of processes thatcontribute to the evolution of galaxies. I will give a historical overview of the differentkinds of Galactic Rings, from observational and theoretical perspectives.

Rings and Disk Resonances 28May09:4540 min

J. Alfonso L. Aguerri

Instituto de Astrofisica de Canarias, Spain

Resonances are places in the disks where stars and gas strongly interact with othergalaxy components. In particular, a large amount of angular momentum can be ex-changed at resonances between the dark matter halo. This can produce importantsecular evolution in disk galaxies. Rings of star formation are common in disk galaxiesat all Hubble types. They can be produced by internal or external galaxy processesand are easily observed in galaxies up to redshift about 1. Rings are related with diskresonances. This implies that they can be used as resonance tracers in the disks duringa long period of the galaxy lifetime. In this talk I will review the main results obtainedin the literature about the relation between rings and resonances in disk galaxies.

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Session II - Structural Properties of Rings

Galaxy Evolution and the Morphology of Galactic Disk Rings 28May10:5525 min

Ron James Buta

The University of Alabama

Galactic disk rings (i.e., features generally known as nuclear, inner, and outer rings)have well-defined properties that suggest that most such rings are molded by internaldynamical processes as opposed to external interactions. In my presentation, I willdescribe the insights into galaxy evolution provided by specific and general aspectsof ring morphology, such as: their typical elongated shapes and preferred alignmentswith respect to bars, the way barred galaxy rings often resemble dominant families oforbits (e.g., as in cuspy inner rings and dimpled outer rings), the existence of doubledinner, outer, and nuclear rings, the apparent morphological continuity of rings andpseudorings, the preference for relatively weak bars in ringed galaxies, the wide rangein intrinsic shapes of inner rings as compared to outer rings, differences between early-and late-type galaxy rings and between barred and nonbarred galaxy rings, the small tolarge misalignments between bars and inner rings occasionally seen, the relation betweenrings and lenses, cases where bars significantly underfill an inner ring, the presence ofmultiple rings having significantly different linear scales and time scales in the samegalaxy, the strong correlation between intrinsic inner ring shape and the distributionof HII regions, and variation of ring properties along the Hubble sequence. Also likelyrelevant to ring evolution are the 3D structure of bars, the distinction between primaryand secondary bars, and the dark spaces seen in many galaxies showing orbit-relatedrings.

Multi-component structural decompositions of barred andringed galaxies 28

May11:2025 min

Heikki Salo, Eija Laurikainen

University of Oulu

Multi-component GALFIT decompositions using 3.6 micron S4G and optical SDSSdata are described. Besides standard bulge+disk+bar components used in the S4Gdecomposition pipeline, we also include models for barlenses (a roundish inner com-ponent embedded in a narrow bar) and for various types of rings. The goal is tocompare how the presence/properties of rings relate to the properties of other struc-tural components. Tests with synthetic images from N-body simulations, treated in asimilar fashion as observations, are also reported, comparing decomposition parametersto model-components derived directly from N-body data.

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Inner and (Mostly) Outer Rings and the Structure of GalacticDisks 28

May11:4525 min

Peter Erwin

Max-Planck-Institute for Extraterrestrial Physics

I will discuss what is currently known about connections between rings, particularlyouter rings, and the underlying radial profiles of galactic disks. Correlations be-tween rings and truncations (Type II profiles, with downbending breaks in the surface-brightness profile) allow us to distinguish between two general models of profile forma-tion. In many early-type disk galaxies, outer rings coincide with downbending breaks,suggesting that ring formation is directly linked to break formation, most likely due toan outer Lindblad resonance. But outer rings also coexist with Type I profiles (whereno break is present), and in some cases with Type II profiles where the break is welloutside the ring, the latter are indications that many truncations, especially in late-type spirals, are due to a different mechanism, such as a star-formation threshold. Iwill also discuss how rings can potentially produce false breaks in Type I profiles, es-pecially in edge-on galaxies, as well as potential connections between outer rings andanti-truncated (Type III) profiles.

The intrinsic shape of galactic structures in ringed galaxies 28May12:1020 min

Jairo Mendez-Abreu

Instituto de Astrofisica de Canarias

In this talk I will review our recent results on the intrinsic three-dimensional (3D)shape of bulges and bars, and its relation with inner and outer ring properties, in astatistically significant sample of galaxies from the CALIFA survey. Our work, basedon the outcome of accurate multi-component structural decompositions of the galaxies,allows to deriving a probabilistic estimation of the 3D shape of individual structures,and it provides a new look at the secular evolution processes taking place in nearbygalaxies. Besides leading to the detection of a merger-induced polar bulge in NGC4698,our analysis revealed that low Sersic indices (or low B/T) bulges have no preferencein being oblate, prolate, or triaxial. On the contrary, bulges with high Sersic indexin early-type galaxies, or in more massive galaxies, are mostly oblate systems. Barsare predominantly prolate spheroids, with a small fraction of triaxial and oblate bars.The typical flattening (intrinsic C/A semiaxis ratio) of the bars in our sample is 0.26,which matches well the typical intrinsic flattening of stellar discs at these galaxy masses.Combining the probability distributions of the intrinsic shape of bulges and bars wepropose a new diagnostic to separate classical and disk-like bulges based on their relativeintrinsic flattening. The connection between the 3D properties of bulges and barswith the presence of inner and outer rings, as well as their implications on the secularevolution of disk galaxies, will be presented in this talk.

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Session III - Dynamics of Ringed Galaxies

A multi-aspect view of bars and of the structures they drive 28May14:0040 min

Lia Athanassoula

Laboratoire d’Astrophysique de Marseille (LAM)

Bars are complex objects. In order to understand them and the structures they driveor are associated with (spirals, rings, lenses etc.) it is necessary to adopt a multi-aspectapproach. The dynamical view starts from simple test particle studies – which are theroots of the corresponding orbital structure theory – to reach fully self consistent state-of-the-art dynamical simulations. This view has been essential to our understanding ofbar formation and evolution and of the properties of the related structures. However,for a more global and yet more realistic view, one needs to add to the picture gas andthe star formation, feedback and cooling which are associated to it. Further progressis possible by including the effects of environment and of accretion. Last but not least,by coupling a hydro + N-body code with a chemical evolution code it is possible toobtain information on the metallicity and the distribution of the various elements inthe bar and in the components related to it. This is particularly crucial at the presenttime, as Gaia and the associated ground-based surveys have started giving results ofunprecedented quality. I will very briefly describe the new understanding achieved aseach of these views is brought in the picture and argue for the necessity of such amulti-aspect view.

Rings and manifolds in barred galaxies. 28May14:4025 min

Merce Romero-Gomez1, Lia Athanassoula2, J.J.Masdemont3

1ICCUB-IEEC; 2LAM; 3UPC-IEEC

Rings appear in galaxies as prominent features having different morphologies and sizes.In this talk, we review the characteristics of outer and inner rings given by Ron Butaand we link them with the manifolds. Manifolds are a set of orbits which are presentin the galactic potential when the axisymmetry of the galaxy is broken by the presenceof, for example, a bar. There are two sets of manifolds at each end of the bar, namelytwo outer and two inner forming the outer and inner rings, respectively. We reviewthat the characteristics of the manifold rings correlate well with the characteristics ofthe bar, providing a prediction tool to astronomers. Finally, we will show up-to-dateapplications of the manifolds in warped-barred galaxies and interacting galaxies.

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Time-dependent resonances in barred galaxies: Implicationsfor ring structures and secular evolution 28

May15:0525 min

Daniel Pfenniger1, Kanak Saha2, Yu-Ting Wu3, Ron Taam3

1University of Geneva, Geneva Observatory; 2IUCAA; Pune; India; 3ASIAA; Taipei; Taiwan

The classical concept of resonance in disk galaxies has been developed with the assump-tion that a single pattern rotating with a constant speed perturbs the galactic potential,allowing to analyze the galaxy dynamics in a time-independent rotating frame. Withthese assumptions resonances, like the corotation and Lindblad resonances, are con-ceptually well defined, and at least one global integral of motion, the Jacobi constant,exists, confining star motion. Barred galaxies, however, have been shown since a longtime (Sellwood & Sparke 1988) to possess at least two patterns rotating at distinctspeeds, the bar and the spiral arms. Each pattern by its gravitational influence torquesthe other and modulates in time at the strongest the bar corotation region and itssurrounding resonances. So the usual corotation and Lindblad resonances lose theirusual meaning, and become “time-dependent resonances”. We have reconsidered thissituation using detailed analyses of fully self-consistent N-body models (Wu, Pfenniger& Taam 2016, 2018, Kanak, Pfenniger & Wu 2018) in order to quantify the dynam-ical incidence of these multiple patterns. To achieve this we needed to develop newmethods to determine the instantaneous and local pattern speeds (Pfenniger, Kanak &Wu 2018). In this paper we will describe the consequences of these works about sec-ular evolution, in particular the action non-conservation limiting the lifetime of rings,and helping stellar migration and, in combination with the bar vertical resonances, theformation of a thick disk.

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Session IV - Poster Session I

Lightning Talks and Viewing

Rings as the shutdown of radial transport 28May5 minJohn C. Forbes1, Mark Krumholz2, Andreas Burkert3, Avishai Dekel4

1Harvard University; 2Mt. Stromlo Observatory; 3University Observatory Munich; 4HebrewUniversity Jerusalem

The local depletion timescale (the ratio of gas surface density to star formation surfacedensity) is a few Gyr throughout galactic disks. This implies that galaxies must beconstantly refueled. If galaxies accrete their gas predominantly at large radii, the centersof galaxies must be resupplied by inward radial transport of gas. A promising candidatemechanism for this transport is gravitational instability. We show here that galaxiesundergoing this process will generically face the low-redshift shutdown of gravitationalinstability, followed by the rapid depletion of gas at their centers, leading to a ring ofstar formation at the interface between the stable and unstable part of the disk.

Kinematics of the ionized gas of the active ring galaxy NGC5728 28

May5 minIsaura L. Fuentes-Carrera

Escuela Superior de Fisica y Matematicas, Instituto Politicnico Nacional

Extended kinematical studies of ionized gas in spiral galaxies have proven to be apowerful tool to identify motions related to the presence of structure such as bars, ringsand spiral arms. In the case of active galaxies, this studies can also shed informationon the inflow of gas from outer regions of a galaxy to its inner/nuclear parts. In thiswork, we present scanning Fabry-Perot observations of the active spiral ringed galaxyNGC 5728. We derive the velocity field of the ionized gas, the dispersion velocity andresidual velocities maps. These fields are compared to morphological features in thegalaxy at different wavelengths The pattern speeds of different density perturbationsare derived and included in our morpho-kinematical analysis of this galaxy.

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Ring galaxies as gravitational probes of pure dark matterhalos 28

May5 minMarja K Seidel1, Barry Madore2, Melissa Jacquart1, Michael Weisberg1

1Carnegie Observatories; 2University of Pennsylvania

What is the Universe made of and how did it evolve? To date, we only know thatbaryons make up barely 5% of the total energy density of the Universe. In the contextof our standard, LCDM, cosmological model, a quarter of the remaining 95% is darkmatter. While our current understanding is that all luminous galaxies are embeddedin large dark matter halos, CDM predicts a wealth of small scale structure which isin tension with current observations of low mass galaxies. This raises the possibilitythat not every dark matter halo hosts a luminous component, as also suggested bythe missing satellites or the too-big-to-fail problems. The challenge is to detect thoseempty dark matter halos via gravitational signatures only. One of the clearest indicatorsof pure interactions are *ring galaxies*, single objects that are unambiguously theresult from head-on collisions of two components. Instead of identifying two luminouscomponents, we look for isolated ring galaxies without any visible companion. We willpresent a suite of hydrodynamic idealized collision simulations between a baryonic diskand a pure dark matter collider (including physical models for star formation and stellarfeedback) to show that these galaxies are consistent with forming from a dark collider.In addition, we aim at detecting these pure dark matter halos through spectroscopicobservations of isolated ring galaxies taken at the 6.5m Magellan telescopes. This is across-disciplinary program between astrophysicists and philosophers of science to studythe unique blend of observation, simulation, theory, and reasoning that allows us toobserve what we cannot see dark matter only visible through gravitational interaction,here by using ring galaxies.

Forging Dark Rings - Radial Clearing of Dust near ResonanceRings 28

May5 minWilliam C. Keel1, Benne Holwerda2, Sarah Bradford3, Anna M. Davis4, Chris Lintott5

1The University of Alabama; 2University of Louisville; 3MTSI; 4Stennis Space Center;5Oxford University

We use ringed and pseudoringed galaxies from the Galaxy Zoo sample of backlit galaxysystems, and in strongly lensing galaxy clusters, to determine the distribution of dustattenuation across resonance-ring structures and associated bars. Use of large back-ground galaxies (and in a few favorable cases, long gravitational-lensing arcs) avoidsthe intercloud favoritism of small background galaxies, although these systems havegiven serendipitous anecdotal data that clear regions exist within resonance rings andadjacent to strong bars. We analyze HST, WIYN, or CTIO imaging for 9 backlit res-onance rings. Some stellar rings are notably poor in dust, with V-band attenuations

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< 0.02. Others are associated with thick dust lanes (V-band transmission < 0.5), buthave nearly transparent surroundings on both sides. This pattern is independent ofwhether there is a strong bar inside the ring.

Comparison of Corotation Resonance Determinations 28May5 minRonald James Buta1, Xiaolei Zhang2

1University of Alabama; 2George Mason Universit

Multiple methods have been proposed in recent years to locate the corotation resonance(CR) in specific galaxies. In this poster, we compare the results from three methods:(1) the streaming phase-reversal (FB) method (Font et al., 2014, MNRAS, 444, L85),where sign changes in the residual velocity field are used to locate CR, (2) the potential-density phaseshift (PDPS) method (Zhang and Buta, 2007, AJ, 133, 2584), where amass surface density map inferred from an image is used to locate CR as sign changesin phase shift versus radius plots, and (3) the gap method (Buta, 2017, MNRAS, 470,3819), where dark gaps between inner and outer rings are assumed to trace the locationof the CR.

Making models of stellar halos to identify merger histories 28May5 minShahram Talei, Jeremy Bailin


Abstract: Mergers are thought to be an important mechanism for forming rings, butwe do not have good tools for identifying the merger histories of ringed galaxies. Stel-lar halos, while containing just a small fraction of stars in every galaxy, in principleencode those merger histories via their mass, metallicity, and structure. However, goodtheoretical models of stellar halos, which are necessary to decode that history, are lack-ing. We are developing a new semi-analytic/N-body simulation code called CoSANG togenerate stellar halos in self-consistent cosmological simulations at low computationalcost, which will be used to interpret stellar halo observations.

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Tuesday, May 29, 2018

Session V - Multi-Wavelength Tracers of Star

Formation I

Star Formation and Stellar Populations in Disk Rings 29May09:0040 min

Johan Knapen

IAC Tenerife

Most rings form stars, and some rings form stars at very high rates indeed. I will reviewstar formation in outer, inner, and nuclear rings, as well as the stellar population inthese classes of rings. Implications for the secular evolution of galaxies will be discussed,as will the use of rings as ’star formation laboratories’.

Multi-wavelength observations of galactic rings 29May09:4040 min

Francoise Combes

Observatoire de Paris

Rings are the location of resonances, where gas accumulates, and new stars form. Theseprocesses can be followed through different tracers, from the radio at low frequency tothe very high X-rays, passing through Halpha, UV or far-infrared as main indicatorsof star formation. The physics of the atomic and molecular gas will be presented, andtheir dynamics, through gravitational torques investigation

Rings in the KPAIR Herschel Survey of Galaxy Pairs 29May10:205 min

Donovan Louis Domingue

Georgia College & State University

The Herschel KPAIR survey provided far-infrared imaging and star formation measuresfor a sample of K-band selected ”major-merger” candidate galaxy pairs in the localuniverse. The survey results suggest that spirals paired with other spirals are more likelyto exhibit enhanced star formation than their counterpart spirals paired with early-type galaxies. Among the spirals in the KPAIR sample, 16 (12%) may be described asdisplaying galactic ring structures. The rings are not resolved in the Herschel imaging.They are distributed among both types of pairs, spiral+spiral (7 rings) and spiral+earlytype (9 rings). The specific star formation rates (sSFR, SFR/Mass) of the individualringed spirals and a comparison to the population of paired galaxies are presented. Theringed spirals have moderate sSFR comparable to that of a non-paired control sampleof galaxies and spirals paired with early-types in all mass bins included in the survey.

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Current Star Formation Rates in Early-Type Disk Galaxieswith Outer Rings 29

May10:255 min

Irina Petrovna Kostiuk1, Olga Sil’chenko2

1Special Astrophysical Observatory of the Russian Academy of Sciences, Russia; 2SternbergAstronomical Institute, Lomonosov Moscow State University, Russia

By using the atlas of stellar rings ARRAKIS (Comeron et al. 2014) we have compiledthe list of early-type, S0-Sb, disk galaxies with outer stellar ring-like features (56 ringsand 61 pseudorings). Current star formation, with the mean age of the young stellarpopulation less than 200 Myr, is present in about a half of the rings. We have determineddust-corrected star formation rates, SFR, as well as SFR surface densities and absoluteAB magnitudes in the ultraviolet (NUV and FUV bands of the GALEX cosmic mission)and (FUV-NUV) colors for the outer rings and for the galaxies as a whole. For furtheranalysis we have took the SFR values averaged over FUV and NUV estimates. Wedemonstrate the relations between the dust-corrected SFR characteristics, UV colors,the galaxy morphological types, and integrated absolute magnitudes for the galaxiesand their ring structures.

Session VI - Multi-Wavelength Tracers of Star

Formation II

Ultraviolet Rings in S0 galaxies 29May11:0025 min

Olga K. Sil’chenko1, Irina Proshina1, Alexei Kniazev1,3, Oleg Egorov3

1Sternberg Astronomical Institute of the Lomonosov Moscow State University; 3SAAO

Despite the general view that lenticular galaxies are ‘red and dead’, they often possess alarge amount of cold gas, and roughly the half of gas-rich S0 galaxies reveal some level ofcurrent star formation organized in ring-like structures. We have undertaken a spectralstudy of a sample of starforming (UV-bright) rings in nearby S0 galaxies to clarify theorigin of the gas and the regimes of star formation in the rings. We have found frequentdecoupling between the gas and star kinematics implying the gas external origin. Alsowe have measured emission-line fluxes in the rings for all strong emission lines in theoptical spectral range, trying to check the mechanism of gas ionization by plotting theemission-line flux ratios onto the diagnostic BPT-diagrams. Most emission-line ringsconfirm the gas excitation by young stars, and we have succeeded to estimate the gasoxygen abundance in these rings through the ‘strong-line method’. To our surprise, thegas oxygen abundance in the rings is always close to solar one, despite the subsolarmetallicity of the underlying old stellar populations and independently on the ringradius.

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The TIMER Project: Time Inference with MUSE inExtragalactic Rings 29

May11:2525 min

Dimitri Gadotti and the TIMER team

European Southern Observatory

The TIMER project is a survey with the integral-field spectrograph MUSE (at the VLT)of nearby barred galaxies with prominent central structures, such as nuclear rings orinner discs. The powerful instrumental setup provides an unprecedented view of thecentral regions of these galaxies. The main goals of the project include: estimatingthe cosmic epoch when discs of galaxies settle, leading to the formation of bars andthe onset of internal secular evolution, testing the downsizing hypothesis for galaxyformation, whereby more massive galaxies are formed first, and estimating the historyof external gas accretion in disc galaxies. I will briefly describe how the survey is builtand the derivation of high-level data products. The latter include maps of the spatialdistribution of parameters describing the stellar line-of-sight velocity distribution, andof mean stellar ages and metallicities. We also derived the spatial distribution of starformation histories and physical properties of the warm/hot phases of the ISM acrossour MUSE fields. In addition, we also obtained the spatial distribution of the kinematicparameters of the warm/hot ISM. I will summarize some of our first results and illustratehow this dataset can be used for a plethora of other scientific applications, e.g., studyingstellar feedback into the ISM, AGN outflows, properties of nuclear and primary bars,stellar migration and chemical enrichment, and the gaseous and stellar dynamics ofthe rich variety of central components in disc galaxies (such as nuclear rings and spiralarms, barlenses, box/peanuts and bulges).

Rings and Rays: a Chandra View of NGC 3081 29May11:5020 min

Walter Peter Maksym1, Martin Elvis1, Pepi Fabbiano1, M. Karovska1, AlessandroPaggi1, John Raymond1, Guido Risaliti2,Thaisa Storchi-Bergmann3, Junfeng Wang4

1Harvard-Smithsonian Center for Astrophysics/Smithsonian Astrophysical Observatory;2INAF Arcetri; 3UFRGS; 4Xiamen University

We present new X-ray observations of the nearby (∼ 34 Mpc) ringed Seyfert 2 galaxyNGC 3081 using the Chandra X-ray observatory. We will discuss reprocessing by theextended circumnuclear gas, some of which is likely associated with the Seyfert bicone,as well as likely reprocessing of the X-rays by the primary star-forming ring.

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Bars, rings, and signatures of secular evolution as seen in theS4G survey 29

May12:1020 min

Simon Dıaz-Garcıa1, Johan Knapen1, Heikki Salo2, Eija Laurikainen2, MartnHerrera-Endoqui2

1Instituto de Astrofisica de Canarias (IAC); 2University of Oulu

Using the Spitzer Survey of Stellar Structure in Galaxies (S4G), we obtain averagede-projected stellar density radial profiles (1D) and mean stellar bars (2D) by stackinghundreds of re-scaled 3.6 micron images of disk galaxies, binned by various fundamentalproperties including the total stellar mass and the prominence of rings/bars. We show,with unprecedented statistical significance, how stellar bars cause the radial spread ofthe disk and enhance the central stellar concentration. We then apply these stackingtechniques to obtain average bars, rings, and disks in Halpha and at UV wavelengths,and to obtain mean colours in optical and near-IR passbands. This allows us to trace theongoing star formation (SF) across galactic disks and in the circumnuclear regions withhigh S/N, detecting low level SF, and thus testing its dependence on local dynamicalconditions (e.g. shear or torques by stellar non-axisymmetries). We find that barscontribute to the redistribution of cold gas and the regulation of SF within galacticdisks. In addition, we shed light on the formation mechanisms of rings and spirals.For a sample of face-on and moderately inclined disk galaxies (i>65) we study thedimensions of resonance rings, ringlenses, and the spiral pitch angles as a function ofthe bar size and strength, using human-supervised measurements, and we compare ourresults to state-of-the-art simulation models. Bar strengths are calculated via Fourierdecomposition of galaxy images, ellipse fitting, and from the gravitational tangential-to-radial forces. We conclude that stellar bars play a role in the formation of spiralarms and rings, although other factors come into play as well.

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Session VII - Ringed and Barred Galaxies

Inner Rings in Barred Galaxies as probes to unravel diskgalaxy evolution 29

May14:0020 min

Marja Kristin Seidel1, Dimitri A. Gadotti2, Paula Coelho3, CharlotteDonohoe-Keyes4, Jesus Falcon-Barroso5, Francesca Fragkoudi6, Bernd Husemann7,Taehyun Kim8, Ryan Leaman7, Gigi Leung7, Adriana de Lorenzo-Caceres5, Marie

Martig4, Inma Martinez-Valpuesta5, Justus Neumann9, Isabel Perez10, MiguelQuerejeta9, Patricia Sanchez-Blazquez11, Glenn van de Ven7

1Carnegie Observatories; 2European Southern Observatory, Munich, Germany;3Universidade de Sao Paulo, Brasil; 4Liverpool John Moores University, United Kingdom;

5Instituto de Astrofisica de Canarias, Espana; 6Max-Planck-Institut fur Astrophysik,Deutschland; 7Max-Planck-Institut fur Astronomie, Deutschland; 8Korea Astronomy and

Space Science Institute; 9European Southern Observatory; 10Universidad de Granada,Espana; 11Universidad Autonoma de Madrid, Espana

The plurality of existing galaxies in today’s Universe remains in many facets an enigmain terms of their individual formation and evolutionary histories. Direct observations ofhigh redshift galaxies and their low surface brightness disks are challenging. Thereforewe use bars as chronometers and their built central structures as tracers to betterunderstand the settling of massive galaxy disks. When disks become massive and coldenough, bars form quickly. Especially during the early formation, bars go through abuckling phase that provokes significant gas inflow to the inner regions. Inner structuressuch as nuclear rings and inner disks are hence formed by this inflow through thebar. By determining the star formation history of such bar-built inner structures innearby galaxies we establish when the major galaxy disk settled into a cold state. Weuse observations of different integral field spectrographs such as WiFeS on the ANU2.3m telescope in Siding Spring Observatory and MUSE at the VLT at ESO, as partof the TIMER team effort. The outstanding spectral resolution (R=7000, R=3000respectively) and spectral coverage combined with the spatial resolution and a highsignal-to-noise-ratio allow us to derive star formation histories while sampling at 10-100pc resolution. From both studies, we obtain a lower limit of when the disks settledof around redshift 2, coinciding with the peak of cosmic star formation. In addition, wefind that about 50% of the stellar mass must have formed at that point, regardless ofenvironment. So when the stars start dominating the potential of the galaxy, it allowsthe disk to settle, to form a bar that funnels gas to the center triggering the formationof central substructures, while quenching star formation in the bar region.

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Feedback from nuclear rings:Caught in the act with ALMA & MUSE-TIMER data 29

May14:2020 min

Francesca Fragkoudi1, Ryan Leaman1, Miguel Querejeta2, Gigi Leung1, DimitriGadotti2

1Max Planck Institute for Astrophysics; 1ESO and the TIMER collaboration

Stellar feedback plays a significant role in modulating star formation, redistributingmetals and shaping the baryonic structure of galaxies. However, the efficiency of itsenergy deposition to the interstellar medium has been difficult to constrain observa-tionally. As part of the MUSE-TIMER project, we have identified a molecular gas anddust shell, in ALMA and HST data, at the leading edge of an energetic outflow fromthe starbursting nuclear ring of the barred galaxy NGC 3351. The total energy budgetof this stellar feedback event is comparable to low-luminosity AGN, and we show, viaanalytic and hydrodynamical modeling of the feedback processes, that stellar radiationpressure can drive the ionized and molecular gas out of the nuclear ring, in accordancewith our observed MUSE kinematics. The morphology of the CO shell and emission-line diagnostics suggest a scenario where magnetic field lines in the dusty ISM aidedits survival as it was launched from the ring by stellar feedback. This system’s uniqueproperties can serve as a useful litmus test for subgrid prescriptions in hydrodynamicalgalaxy simulations, as well as shed light on the feedback processes occurring in thecentral regions of disk galaxies.

On the origin of nuclear rings in barred galaxies 29May14:4020 min

Mattia Carlo Sormani1, Francesca Fragkoudi2, Emanuele Sobacchi3, Matthew Ridley4

1University of Heidelberg, Germany; 2MPA Garching, Germany; 3Ben-Gurion University ofIsrael; 4University of Oxford

We present a novel and simple dynamical theory for the origin of nuclear rings inbarred galaxies. In analogy with the usual theory of accretion discs, the theory is basedon shear viscous forces among nested annuli of gas. However, in contrast with theusual case, the gas follows non circular orbits in a barred potential. This qualitativelychanges the usual picture: instead of transporting angular momentum outwards whilemass is accreted inwards, a trapping region is created where a stable and infinitely-longlived ring can survive. Our theory allows to predict the size of the nuclear ring giventhe underlying gravitational potential. The predicted radius in general significantlydiffers from the radius of the inner Lindblad resonance. The theory could provide apowerful tool to constrain the gravitational potential of barred galaxies, in particulartheir pattern speed.

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Effects of Disk Mass and Gas Fraction on the Formation ofNuclear rings 29

May15:0015 min

Woo-Young Seo1, Woong-Tae Kim1, Phil Hopkins2

1Seoul National University; 2Caltech

To study the formation and evolution of stellar bars and gaseous nuclear rings in re-alistic environments, we use GIZMO, a mesh-free hydrodynamic code, to run fullyself-consistent three-dimensional simulations of Milky-Way sized isolated disk galaxiesconsisting of a stellar disk, gaseous disk, and live dark halo. Our simulations incorpo-rate a prescription for star formation and feedback via supernovae and stellar winds.We find that the ring size varies with time as it is affected by the bar strength andthe central mass concentration (CMC). A ring is very small when it first forms due toa small CMC and initial bar growth. Subsequent bar weakening as well as enhancedCMC make the ring grow in size afterwards. The rings form faster in more massivedisks, and are larger in disks with a larger gas fraction. The bars and nuclear ringsformed in our models have properties similar to those in the Milky Way.

Ansae in barred ringed galaxies 29May15:1520 min

Ivan Katkov1, Alexei Kniazev2, Olga Sil’chenko1

1Sternberg Astronomical Institute, Lomonosov Moscow State University; 2South AfricanAstronomical Observatory

The general view of galaxy formation and evolution includes bars as the major driversof the internal secular evolution of galaxies. The bars are very frequent phenomena:about one-third of all disk galaxies are strongly barred and an additional one-thirdare moderately barred. Often bars in galaxies are accompanied by rings and ansaephenomena at the end of bars. The ansae are bright enhancements at the ends ofbar which are thought to be formed in the secular evolution phase (> 5Gyr) of diskgalaxies. The ansae are frequent phenomena since 40% of early-type disk galaxies revealthis feature but their properties and dynamical significance are still poorly understood.Based on the optical spectroscopic observations at SALT (South Africa) telescope westudied the stellar populations of ansae regions in 7 barred disk galaxies. All consideredgalaxies possess rings at the end of bars except one where the ring is less prominent.We found that ansae regions are significantly distinguished in the stellar metallicities inall galaxies. At the same time these regions do not reveal peculiarities in the stellar ageprofile. We discussed how these findings provide additional important information thatshould be taken into account for detailed gaseous-stellar dynamical models to restrictthe bar evolution.

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Unveiling the nature of barlens structures with TIMER 29May15:3520 min

Isabel Perez and the TIMER collaboration

University of Granada

Boxy/peanut bulges are considered to be part of the same stellar structure as bars andboth could be linked through the buckling instability. The Milky Way is our closestexample. These B/P bulges are ubiquitous, 40% of galaxies would present this type ofcentral structures that have been linked to the bar. Some recent works have associatedbar lenses to B/P bulges as seen face-on. Whether barlens are characterized by bar ordisc kinematics and stellar populations closer to those of a bar or whether they are sim-ilar to the disc still remains unknown. Both the kinematics and the stellar populationinformation would help to discern the nature of these structures and determine whetherthey are the product of buckled bars or not. We will present the kinematics, stellarage distributions on the barlens region of 13 galaxies with MUSE/VLT data from theTIMER project.

Session VIII - Poster Session II

Lightning Talks and Viewing

Barlenses in the CALIFA survey 29May5 minEija Irene Laurikainen1, Heikki Salo1, Jarkko Laine2, Joachim Janz1

1University of Oulu, Finland; 2University of Hamburg, Germany

Barlenses are studied in the Calar Alto Legacy Integral Field Survey (CALIFA: Sanchezet al. 2012) of 1064 galaxies. They are recognized as lens-like structures embedded inbars, and are suggested to be the face-on counterparts of the Boxy/Peanut/X-shapedbars. Barlenses and/or X-shapes appear in 25% of the CALIFA galaxies, which galaxieshave often inner rings or inner lenses. Detailed multi-component decompositions arecarried out, fitting besides the bulges, disks and bars, also the barlenses with a sep-arate function. Similar decompositions are performed for simulation snapshots, takenfrom models in which barlenses formed during the galaxy evolution. For a half of thedecomposed galaxies stellar populations and metallicities were studied using the CAL-IFA V500 grating data-cubes. We find that most of the flux of the photometric bulge(i.e. flux above the disk extrapolated to the galaxy center) in the studied galaxies isdominated by a barlens.

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The Nature of Star Formation within Bars 29May5 minJustus Neumann1, Dimitri Gadotti2, Lutz Wisotzki1, Bernd Husemann3, and CARS

collaboration1Leibniz-Institut for Astrophysik Potsdam; 2ESO; 3MPIA Heidelberg

The presence and nature of galaxy bars is in close connection to all secularily builtstructures. Understanding the formation and evolution of bars furthers our knowledgeabout their impact on and interplay with co-existing secular galaxy components suchas galactic rings. Various authors have observed a lack of star formation within the barregion of some barred disc galaxies, while other galaxies show significant star formationin their bars. The absence of star formation can theoretically be explained by shear. Gasclouds that are traveling along the bar are subject to a velocity gradient perpendicularto the bar mayor axis. The resulting shear can disrupt the clouds and prevent them tocollapse and form stars. With this poster, I would like to show how 3D spectroscopy canbe used to connect spectroscopic parameters with photometric properties in order tostudy how star formation can be inhibited in some galaxy bars. We use spatially resolvedHalpha flux from VLT/MUSE observations of 16 nearby barred galaxies together with adetailed two-dimensional photometric image decomposition to explore how the absenceand presence of star formation within the bar is connected to structural properties ofthe bar and the host galaxy.

The Secular Origin of the Milky Way bulge 28May5 minFrancesca Fragkoudi1, Paola Di Matteo2, Misha Haywood3, Mathias Schultheis3,

Sergey Khoperskov3, Ana Gomez2, Francoise Combes2

1MPIA; 2Observatoire de Paris; 3Laboratoire Lagrange - OCA

Examining the chemo-morphological relations of stellar populations in the Milky Way(MW) bulge can provide clues to the formation history of our Galaxy, and of discgalaxies in general. To explore the possible disc origin of the MW bulge populationsI used an N-body simulation where the bulge is formed secularly through the verticalheating of a bar, which is formed from a composite thin+thick disc. In this model thethick disc is metal-poor, alpha-enhanced, massive and centrally concentrated, as hasbeen shown to be the case for the chemically defined thick disc of the Milky Way. Themodel is compared to data of the bulge obtained with the near infrared spectroscopicsurvey APOGEE. As I will show, all the chemo-morphological relations examined arewell reproduced by the model, as is the metallicity distribution function (MDF) ofthe MW bulge as a function of longitude and latitude. These findings show that thechemical composition of the MW bulge is consistent with it being made up of thin+thickdisc stellar populations. I will discuss these results in light of the mounting evidence –from morphology, kinematics and chemistry – of the MW bulge’s pure disc (i.e. secular)origin.

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2D metallicity gradients and how they depend onsubstructures in MaNGA galaxies 29

May5 minAmy Michelle Jones, Preethi Nair, and the MaNGA team


Many galaxies have a metallicity gradient, however there is a large scatter about theslope of this gradient. Typically the galaxy is azimuthally averaged to look only at the1D metallicity profile as a function of radius. With IFU observations, we no longerneed to azimuthal average, but instead can use the 2D metallicity map to describemetallicities in galaxies. With SDSS IV MaNGA observations, we can disentangle thescatter in the 1D profile by measuring metallicity gradients along certain substructureswithin the galaxies, e.g. spiral arms and bars. By looking at the gradients along thestructures, we hope to minimize the scatter and compare these different gradients. Wewill use the full 2D information to find quantitative parameters, such as asymmetry,M20, and MID diagnostics, to describe the metallicity distribution within galaxies andsee how these correlate with other galactic properties and structure.

NGC 4622: A clear example of spiral density wave starformation in a ring galaxy 29

May5 minGene Gilbert Byrd

Dept. of Physics and Astronomy, The University of Alabama

Our HST NGC 4622 images are discussed; heritage.stsci.edu/2002/03/index.html. Nor-mal to the line of nodes, the SE edge is turned toward. The SW away ∼19 deg...TheNE node line recedes and the SW approaches so orbits are clockwise on the sky. TheBeads on a string NE arm (1) winds inward CCW. Gas clouds enter the more slowlyturning arm on the CONVEX side outside an outer co-rotation circle. (OCR=36, 5.16,1kpc). These become short-lived associations on the CONCAVE side Side switchinghappens going inward along (1). A bright association occurs in the MIDDLE of thearm at the OCR where the CW orbital angular rates of gas clouds and the arm angularrate match. Within the OCR, associations of arm (1) are on the CONVEX side as thearm catches up on slower gas clouds which light on the other side. Closer in, the NEportion of arm (2). is also inside the OCR. Associations on the convex side are clearerfor this less obscured portion. Yet to be ignited absorbing clouds are visible inside arm(2) at NE. An unusual rising rotation curve is observed crossing the arm pair OCR.A leading arm pair would be amplified there. If there is an extended massive darkmatter halo to create the rising curve.. A puzzling single trailing arm winds outwardCCW from center, opposite through another, inner ICR=22. There the rotation curveis flat which would amplify a trailing arm. Color observations show density wave phaseand side switching at ICR. A merger-induced oscillating nucleus would have a one-foldperturbation strong near the center with a two-fold perturbation still strong farther

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out, triggering the two arm kinds. Alar Toomre christened us (ref) The backward as-tronomers who found the backward galaxy. One of us, Tarsh Freeman, passed away atage 66 on Jan. 19, 2018. Perhaps he is now getting to see up-close what is happening inNGC 4622.. Ref for above discussion. G. Byrd, T. Freeman, S. Howard, R. Buta 2008.AJ., 135, 408. See http://www.researchgate.net/profile/Gene Byrd2 for this poster.

Arm structure, bars and rings in 3-armed spiral galaxies 29May5 minColin Hancock, Bill Keel


We examine the structure of 180 candidate 3-armed spiral galaxies from the Galaxy Zoo2 results. We use the SpArcFiRe web interface to quantify the pitch angle, separation,and radial extent of distinct arms. As suggested by visual inspection, the patterns rangefrom 3-fold symmetric arms to 2-armed patterns with an additional or branched armof comparable length and brightness. The visual impression that these are two distinctgroups is difficult to test quantitatively, because it is common for the arms to have quitedifferent pitch angles (and thus radius-dependent separations). An unexpected outcomeis that bars (and resonance rings around the arms) are no less common in 3-armed spiralsthan in the overall lisper population, the 3-armed dominant patterns manage to coexistwith very strong twofold driving patterns in the inner parts of these disks. Likewise,some clear 3-armed spirals have large close companions and tidal disturbances, at oddswith the idea that m=3 structures grow in the absence of external perturbations.

How do spiral arm contrasts relate to bars, disc breaks andother fundamental galaxy properties? 29

May5 minAdrian Bittner1, Dimitri A. Gadotti2, Bruce G. Elmegreen3, Lia Athanassoula4,

Debra M. Elmegreen5, Albert Bosma4, Juan-Carlos Munoz-Mateos6

1University Observatory Munich; 2European Southern Observatory, Garching, Germany;3IBM Research Division, T.J. Watson Research Center, USA; 4Aix Marseille Universite,CNRS, LAM, Laboratoire d’Astrophysique de Marseille, France; 5Vassar College, USA;

6European Southern Observatory, Santiago, Chile

To better understand the role that spiral arms and bars play in the secular evolutionof disc galaxies, we investigate how the properties of spiral arms relate to other funda-mental galaxy properties, including bars and disc breaks. We use previously publishedmeasurements of those properties, and our own measurements of arm and bar contrastsfor a large sample of galaxies, using 3.6 micron images from the Spitzer Survey of Stel-lar Structure in Galaxies. Galaxies with flocculent arms are clearly distinguished fromother spirals, especially by their lower stellar mass and surface density. Multi-armed

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and grand-design galaxies are similar in most of their fundamental parameters, exclud-ing some bar properties and the bulge-to-total ratio. Based on these results, we revisitthe sequence of spiral arm classes, and discuss classical bulges as a necessary conditionfor standing spiral wave modes in grand-design galaxies. We find a strong correlationbetween bulge-to-total ratio and bar contrast, and a weaker correlation between armand bar contrasts. Barred and unbarred galaxies exhibit similar arm contrasts, butthe highest arm contrasts are found exclusively in barred galaxies. Interestingly, thebar contrast, and its increase from flocculent to grand-design galaxies, is systemati-cally more significant than that of the arm contrast. We corroborate previous findingsconcerning a connection between bars and disc breaks. In particular, in grand-designgalaxies, the bar contrast correlates with the normalized disc break radius. This doesnot hold for other spiral arm classes or the arm contrast. Our measurements of armand bar contrast and radial contrast profiles are publicly available.

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Wednesday, May 30, 2018

Session IX

Barred Galaxies Dynamics

Collective Effects and Secular Dynamical Evolution ofGalaxies 30

May09:0530 min

Xiaolei Zhang1, Ron Buta2

1George Mason University; 2University of Alabama

Growing observational evidence points to the likelihood of a general trend of galaxymorphological evolution along the (inverse) Hubble sequence. The chief dynamicalmechanism responsible for this evolution, however, had been a highly debated subject.We show that when galaxies are analyzed as globally self-consistent dynamical systems,which admit unstable density wave modes, emergent new meta-laws appear which in-validate the differential treatment of classical approaches based on Boltzmann’s kineticequation and its descendants (i.e., the stellar dynamical equation and the Eulerian fluidequations). The collective interactions of N-particles in a galaxy disk lead to the forma-tion of collisionless shocks at the density wave crest, which interact with the basic statedisk matter, leading to the secular redistribution of disk mass (manifested as the mor-phological evolution of galaxies along the Hubble sequence), as well as the damping andstabilization of the growing wave amplitude to achieve quasi-steady state of the wavemode. Analyses of near- and mid-infrared images of galaxies confirm the predictionsof the dynamical theory, and lead to practical applications of the so-called potential-density phase shift (PDPS) approach as an accurate and efficient method for locatingcorotation resonances in spiral and barred galaxies, as well as for calculating the secularmass flow rates in galaxies for building up the Hubble sequence within cosmologicallyrelevant timescales. Applied to the ringed barred spiral NGC 3351, the PDPS methodinterprets the bar as being “superfast”, and the ring as due to the snow-plough effectfrom the interaction of the inner bar and the outer spiral modal patterns, each havingdistinct pattern speed. This result differs from that of the usual passive orbit analysis,which interprets SB inner rings in terms of inner 4:1 resonance with a normal (relativelyslow) bar.

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Constraints on angular momentum changes for corotatingstars 30

May09:3520 min

Kathryne J. Daniel

Bryn Mawr College

Stars that corotate with a non-axisymmetric structure, like a spiral pattern or bar, canbe trapped in an orbital family called horseshoe orbits. In the last decade, these orbitshave been of particular interest when they are induced by time-dependent amplitudespiral arms in the disk, thus leading to radial migration of stars. Should radial migrationbe an efficient process, it could play an significant role in the chemical and structuralevolution of disk galaxies. I will present results from my recent analytic explorationsaimed at constraining the efficiency of this process. In these investigations we appliedan analytic criterion to define the phase-space volume for horseshoe orbits to a variety ofdisk galaxy models with various energy and angular momentum distributions. We findthat kinematically colder populations and higher amplitude perturbations have a higherfraction of stars in horseshoe orbits, while higher amplitude perturbations also inducelarger maximum changes in individual angular momenta. I will also present preliminaryresults suggesting that these maximum distances are likely limited by overlap with otherdynamical resonances in the disk, even in the case of a single perturbation. I will discussimplications and compare them with observational and simulated data.

Annular kinematic segregation of galaxy disks 30May09:5520 min

Joan Font, John E. Beckman

Instituto de Astrofisica de Canarias, Spain

Our technique (FB) for the precise measurement of corotation radius, based on usingthe phase change by of the radial component of stellar or gas motion expected atthis radius, has recently been compared with the classical Tremaine-Weinberg methodshowing complete agreement where both could be applied. However FB is more gener-ally applicable and can be used over complete galaxies, from the innermost zones withnuclear bars to the outermost spiral arms. When this is done, the result is to uncovermore than one corotation radius per galaxy. We have found corotations at roughly 2.5times the radius of the ends of nuclear bars and (in the same objects) at between 1 and2 times the radius of the ends of the major bars. But beyond this there are corota-tions associated with radially separated annuli containing segments of spiral arms. Thenumber of corotations per galaxy ranges from 1 to 7 in a sample of some 150 objects.We have also found a virtually universal coupling pattern between the annuli such that,given two corotations, CR1 and CR2, the Outer Lindblad Resonance of CR1 falls atCR2 and the inner 4:1 ultraharmonic resonance of CR2 falls on CR1. These couplingpatterns occur at least once in over 70% of observed disks, with a maximum occurrenceof 4 such patterns in a single galaxy. This work marks only the beginning of applicablestudies of angular momentum distribution and evolution in disk galaxies.

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Bar pattern speed estimates using the Tremaine-Weinbergmethod in MaNGA galaxies 30

May10:1515 min

Luis A Garma, Erik Aquino-Ortiz, Hector Hernandez-Toledo, Mariana Cano-Diaz,Octavio Valenzuela, Sebastian F. Sanchez

Instituto de Astronomıa - UNAM

Understanding the role stellar bars play in the dynamical evolution of galaxies hasbeen a challenging problem, in part because of the difficulty in estimating fundamentalparameters like the bar pattern speed. Based on the continuity equation, the Tremaine& Weinberg (1984) method is the only direct method to measure the bar pattern speed,however it has only been applied to a limited number of galaxies. In this talk, I willdiscuss how we have applied this method to MaNGA galaxies emphasizing the treatmentof the associated errors in different steps of the methodology.

Session X

Properties of Barred Galaxies

Spatially Resolved Metallicity Distributions in Barred andUnbarred Galaxies: Implications for Galaxy Evolution since

z∼2 30May11:0020 min

Shardha Jogee1, Kyle Kaplan2, Lisa Kewley3, Guillermo A. Blanc4, and the VENGAcollaboration

1University of Texas at Austin; 2University of Arizona; 3Australian National University;4Universidad de Chile

We present a study of the spatially resolved ionized gas metallicity in nearby barred andunbarred spirals using integral field spectroscopic (IFS) data from the VIRUS-P Explo-ration of Nearby Galaxies (VENGA) survey, which has excellent high spatial resolution(median 380 pc) and wide coverage from the bulge to the outer disc. Contrary to someearlier studies, which claimed a difference in metallicity gradient between barred andunbarred galaxies, we find that isolated barred and unbarred spirals exhibit similarlyshallow gas metallicity profiles from the inner kpc out to large radii. These resultsimply that present-day stellar bars are not the primary agent responsible for flatteningmetallicity gradients, and have associated implications for cosmological models of gasinflows and stellar feedback at z>2. We also find that the metallicity gradients in ourz ∼ 0 massive spirals are markedly shallower than published gradients for lensed lowermass galaxies at z ∼ 1.5 - 2.0. This type of evolution in metallicity gradients sincez∼2 is better reproduced in cosmologically motivated hydrodynamical simulations withconventional stellar feedback (e.g. in MUGS simulations) than those with enhancedstellar feedback (e.g., MaGICC simulations).

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The Origin of Bars in Quenched Disk Galaxies: A MaNGAView 30

May11:2020 min

Amelia K. Fraser-McKelvie, Alfonso Aragon-Salamanca, Michael Merrifield

University of Nottingham

Rings, bars, and spiral arms are transient phenomena that occur in a large proportion ofquiescent disk galaxies. Whether these enhanced stellar densities are hangovers from agalaxy’s days as a spiral, or have formed since transformation to early-type is unknownhowever. To investigate this, we examine a population of strongly-barred quiescentgalaxies within the Mapping Nearby Galaxies at APO (MaNGA) galaxy survey, manyof which also possess what appear to be loose spiral arms and ansae. We proposetwo possible origins for these galaxies: 1) They are passive spiral galaxies that havebeen quenched with the help of bar structure. 2) They were lenticular galaxies thathave formed a bar instability and in doing so, produced tidal features that look similarto spiral arms. We utilize spatially-resolved spectroscopy from the MaNGA survey todetermine the stellar populations of the bar, arm and interarm regions of these galaxies.Preliminary results suggest that for most galaxies, the entirety of the disk quenchedsimilarly recently, advocating for a common ancestor for all galaxy structure. Theseresults will aid in the understanding of bar and ansae formation and their role in galaxyquenching.

Determining the epoch of bar formation 30May11:4015 min

Charlotte Donohoe-Keyes, Phil James, Marie Martig and the TIMER Collaboration

Astrophysics Research Institute, Liverpool John Moores University

Bars in early-type spiral galaxies are surrounded by a region of suppressed star forma-tion, which we term the star formation desert. That region itself is usually embeddedwithin a younger ring. With a sample of zoomed in cosmological simulations we ana-lyze the connection between bars, rings and star formation deserts. In particular, usingsimulated galaxies with bars forming at different times, we find that the cessation ofstar formation within the star formation desert coincides with the epoch of bar forma-tion. This supplies a novel method to determine when bars formed, which we applyto MUSE data of nearby barred galaxies from the TIMER collaboration. This givesnew insights into the timescales of bar formation and the interplay between bars, starformation deserts, rings and their host galaxies.

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Secular evolution driven by double-barred systems in theTIMER survey 30

May11:5520 min

Adriana de Lorenzo-Caceres, and the TIMER team

Instituto de Astrofısica de Canarias (IAC)

The TIMER project (Time Inference with MUSE in Extragalactic Rings) is a well-designed survey of barred and ringed galaxies with noticeable central structures, suchas inner bars and nuclear rings, which are considered as footprints of secular evolution.The current TIMER sample is composed by 19 galaxies, three of them being confirmeddouble-barred systems. In this talk I will present unprecedented results on double-barred galaxies provided by the superb integral-field spectroscopic TIMER data. Weconfirm the ubiquitous appearance of sigma-hollows in double bars, in agreement withthe recent scenario of an intrinsic vertical velocity dispersion feature for their origin.A detailed study of the star formation histories, in combination with two-dimensionalmulti-component photometric decompositions, allows us to dissect double-barred galax-ies and to discern the nature of inner bars. We find that they have been secularly as-sembled after the outer bars, but still are relatively old systems. A slight rejuvenationof the very central regions due to a non-efficient gas inflow through the inner bars isalso observed. I will discuss all these results in the context of the secular evolutionnature of central structures in ringed galaxies.

Photometric Properties of Bars in Low Surface BrightnessGalaxies 30

May12:1515 min

Wesley Peters, Rachel Kuzio de Naray

Georgia State University

We present results on photometric properties of bars in low surface brightness galaxies(LSBs). Given the expected structure of their dark matter halos, these galaxies arethought to be quite stable against bar formation. However, because barred LSBs aretypically avoided in kinematic studies and because LSBs (of all types) are usuallymissing from large scale surveys of galaxies, the bars in these systems are not wellunderstood or measured. Using optical B and I-band images, we have characterized thelength, strength, and corotation radius of bars in nearly twenty LSBs. We find that thebars in our sample are weaker than those in “normal” high surface brightness galaxies(HSBs), but comparable in length and relative bar pattern speed. We place these barsinto context with those found in HSBs, as well as with expectations from numericalsimulations.

Thursday, May 31, 2018

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Session XI - Spiral Structures in Disk Galaxies

Formation and Evolution of Spiral Structure in Disk Galaxies 31May09:0040 min

Elena D’Onghia

University of Wisconsin-Madison

I will review the various mechanisms of formation of spiral structure in disk galaxies,with emphasis on the longevity of the arms. This has interesting consequences for manyaspects of disk evolution, including the currently popular claim that stars such as ourSun can radically migrate from their birthplaces due to the action of time-variable spiralarms, a process termed stellar radial migration. I will also review the relevance of thecontinuing bombardment of galaxy disks by dark-matter clumps and larger satellites inproducing vertical oscillations of stellar disks, rings in the disk plane, and wobbles anddiscuss the implications for our Milky Way.

The properties and origins of spiral structure across thegalaxy population 31

May9:4020 min

William Clifford Keel1, Steven Bamford2, Ross Hart2, and the Galaxy Zoo team1The University of Alabama; 2University of Nottingham

This talk presents the key results of an extended study combining Galaxy Zoo visualmorphological information with automated spiral arm pitch-angle measurements, bulge-disc decompositions and multi-wavelength photometry, for a sample of several thousandgalaxies. We find that galaxies with different numbers of spiral arms are distributedsimilarly in terms of stellar mass, environment and specific star-formation rate. On theother hand, those with two-spiral arms are significantly redder and contain less gas thantheir multi-armed counterparts. We reconcile this disparity by observing that two-armspirals are more efficient at converting gas into stars, but that a larger proportion ofthis star-formation occurs in highly obscured regions. This points to distinct differ-ences in the mechanisms responsible for two- and many-armed spiral structure. In theabsence of bars and tidal interactions, a popular mechanism for spiral arm formation isvia swing-amplification. This model makes predictions for spiral arm properties, whichdepend on the relative masses and sizes of a galaxy’s stellar and dark matter compo-nents. We combine structural measurements and scaling relations in order to predictarm properties for the unbarred galaxies in our sample, which we then confront withobservations. For one half of these galaxies, primarily those with two-arms, the ob-served arm numbers are inconsistent with expectations from swing-amplification. Forthe other half, the predicted distribution of arm properties is reasonable. Furthermore,providing we adopt inner halo profiles which depend on galaxy mass and size, in a

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manner predicted by recent hydrodynamical simulations, we obtain a good correlationbetween observed arm properties and those predicted by the model. We conclude thatan identifiable half of unbarred spiral galaxies contain arm patterns dominated by sec-ular swing-amplification, while the remainder are driven by tidal interaction or densitywave mechanisms.

Study of stellar formation and evolution in spiral galactic disks 31May10:0020 min

Carmen Sanchez Gil1, Emilio J. Alfaro Navarro2, Enrique Perez2, Miguel Cervino3,Joss Bland-Hawthorn4, Heath Jones5

1University of Cadiz, Spain; 2Instituto de Astrofisica de Andalucıa-CSIC, Granada, Spain;3Instituto de Astrofısica de Canarias, Tenerife, Spain; 4Sydney Institute for Astronomy,

University of Sydney, Australia; 5Australian Astronomical Observatory, Australia

Spiral arms formation is still an open problem. Even in our Galaxy, the number ofspiral arms and its origin is not well-known. It could even coexist different or severalmodes of formation in the same galaxy. On the one hand, we present hierarchicalbayesian inference models to determine the age in disks of nearby and nearly face-on,spiral galaxies. For a sample of 9 galaxies Halpha data are taken with Taurus TunableFilter, (TTF), ultraviolet band far UV or FUV from GALEX, and infrared bands at24, 70 and 160 microns from Spitzer surveys. This is, we present the burst ages foryoung stellar populations in a sample of nearby and nearly face-on galaxies, provingenough spatial resolution of the galactic disks. And Halpha to FUV flux ratio is a goodrelative indicator of the very recent star formation history (SFH). Through syntheticstellar populations model, we obtain theoretical Halpha/FUV ratios to compare withour observed flux ratios, and thus to estimate the ages of the observed regions. Due tothe nature of the problem, it is necessary to take into account the mean uncertainties,and the interrelationships between parameters when the Halpha/FUV flux is obtained.We propose a Bayesian hierarchical model, where a joint probability distribution isdefined to determine the parameters (age, metallicity), from the observed data. Thejoint distribution of the parameters is described through an i.i.d. (independent andidentically distributed random variables), generated through MCMC (Markov ChainMonte Carlo) techniques. The sample associated shows a variety of morphologies, asspiral arms and rings among others. The age patterns obtained for these galaxiesindicate the great diversity of physical mechanisms that seem to act in the modelingof the star-to-large formation process scale. We analyze with more detail the possibleorigin of such structures as a function of spatial patterns from their age maps. Thecomparison of the age patterns obtained with those predicted by Dobbs & Pringle(2010) for the distribution of young clusters allows us to conjecture about the differentphysical mechanisms that excite and maintain the spiral arms. The casuistry is varied:training stellar spiral arms mainly induced by density waves (M100, M74 and M51),circumnuclear rings (M94), age gradients affecting the entire galaxy (from West to East,M63), or radial age gradient (M74), or dominated by HII regions. N1068 seems to be a

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good and clear example, as outcome of our results, that AGN interaction with gas canreach larger scales (up to 7-8 kpc from the nucleus). Finally, we address the study of thedetection in Halpha of a radial corrugation in the vertical velocity field in disks of nearlyface-on, spiral galaxies. With the aim of studying the corrugated velocity patterns interms of the star formation processes, we describe the geometry of the problem andestablish its fundamental relationships. In particular, the relationship between densityof the ionized gas and the amplitude of the corrugation in speed. Two large groups havebeen found. In one of them the velocity and gas density show a out of phase correlationby a distance of a few hundred pc. The another class does not seem to show a well-defined pattern. These two classes show different physical properties of the ionized gasdefined from different diagnostic diagrams (Sanchez-Gil et. al 2015). The origin of thecorrugations is still matter of debate. Corrugations are closely link, as cause/effect, tothe large scale star formation processes: density waves, tidal interactions, collisions ofhigh velocity clouds with the disk, or a galactic bore generated by the interaction ofa spiral density wave with a thick gaseous disk, as modeled by [Martos & Cox 1998,Martos et al. 1999], etc. Which mechanism is the origin of disk corrugations is still anopen problem.

A new technique to measure pattern speeds of spirals inMaNGA 31

May10:2015 min

Tom Peterken, Michael Merrifield, Alfonso Aragon-Salamanca

University of Nottingham

The pattern speed is one of the defining properties of morphological structure such asspiral arms, which in turn dictates the locations of ring features. Unfortunately, it isnotoriously difficult to measure, as it only has an indirect connection to measurableparameters such as the stellar rotation speed. Here, we present an entirely new methodto determine this fundamental quantity by directly measuring the offset between thelocation of the arm and young stellar component emerging from it. A pilot applicationto SDSS-IV MaNGA data shows that this approach has real promise, and, as a bonus,also gives an independent direct measure of the timescale for star formation.

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Session XII - Collisional Ring Galaxies

Accretion-generated rings: coplanar and non-coplanarstructures 31

May11:0540 min

Alexei Moiseev

Special Astrophysical Observatory, Russian Academy of Sciences

The majority of known rings in galaxy disks are formed under the action of “classical”dynamical mechanisms like bar resonance or head-on collision with a satellite. How-ever, a small fraction of galactic rings can be explained by a capture of the externalmatter like dwarf companions, external gaseous clouds or even cosmic web filaments. Inthis review, we consider observational properties of the accretion-generated rings andrelated objects in order to constrain different scenarios of their origin. In particular,we present new results of the study of gas kinematics and chemical abundance in polarring galaxies based on the long-slit and 3D spectroscopy with the scanning Fabry-Perotinterferometer at the Russian 6-m telescope. It’s important to emphasize that the ex-ternal accretion can produce not only non-coplanar multi-spin structures (external andinner polar rings and disks) but also rings of star formation that are coplanar with themain galaxy disk. Perspectives and first results of modern 3D-spectroscopic surveys ofgalaxies in studying accretion rings are discussed.

The Star-forming ISM in Collisional Ring Galaxies 31May11:4525 min

James Lloyd Higdon1, Sarah J. U. Higdon1, Richard J. Rand2, Sergio Martin Ruiz3

1Georgia Southern University; 2University of New Mexico; 3ESO

Collisional ring galaxies provide interesting perspectives on the triggering/quenching oflarge scale star formation and the destructive effects of massive stars on molecular cloudcomplexes. I will present new results utilizing high resolution radio, sub/millimeter,infrared, and optical data that illustrate the role of gravitational stability and divergentgas flows in star formation regulation, factors influencing the ISM’s molecular fraction,and evidence of peculiar star formation laws and efficiencies in two highly evolved ringgalaxies: Cartwheel and the Lindsay-Shapley ring.

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This Cartwheel’s on Fire: Gas Flows and Star Formation inCollisional Ring Galaxies 31

May12:1020 min

Florent Renaud

Lund Observatory

Collisional rings represent a unique laboratory to study galaxy evolution. Despite anorbital configuration making them rare, such systems yield much simpler morphologyand kinematics than classical mergers, and can thus be used to better understand thephysical processes acting during interactions. In this view, and to help the interpreta-tion of increasingly richer observational dataset, in particular from IFUs, we need newgeneration, predictive simulations of rings. In this talk, I will use a recently publishedparsec-resolution hydrodynamical simulation of the Cartwheel galaxy to illustrate themain physical processes at stake. I will present results on the processes of ring for-mation, in particular the prediction of the presence of a cylindrical structure abovethe ring, and also galactic-wide gas flows and collision-driven starburst activities. Theresults from this simulation and its forthcoming siblings could help bring observers andtheoreticians together to analyze data and to prepare the next observation campaigns.

Session XIII - Rings in Milky Way and Local Group

Galaxies

Understanding the nuclear ring and other gaseous features ofthe Milky Way 31

May14:0525 min

Juntai Shen1, Zhi Li1, Ortwin Gerhard2

1Shanghai Astronomical Observatory; 2MPE

The gas inflow pattern in the Milky Way is mainly dictated by its bar and spiral arms.We study the nuclear ring/disk and other gaseous structures in the Milky Way withhigh-resolution hydro-dynamical simulations. Our model can reproduce the morphologyand kinematics of many key observational features such as the nuclear ring, Bania’sClump, the Connecting arm, the Near and Far 3-kpc arms, the Molecular Ring, andthe spiral arm tangent points. We also test the dynamical effects of the nuclear bulge,the main spiral arms, and the long bar component on key gaseous structures. Ourresults may have important implications for understanding the dynamical structures ofthe Milky Way and other nearby barred galaxies.

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Are the Near and Far 3 Kiloparsec Arms of the Milky WayActually A Galactic Ring? 31

May14:3020 min

Robert Benjamin

University of Wisconsin-Whitewater

Whether the Galaxy contains a stellar ring, i.e. an overdensity of stars surroundingthe central bar, is uncertain. There is no compelling evidence for a stellar ring in themass distribution. But there are two structures that could arguably be identified asan interstellar, star-forming ring. The first is the Molecular Ring (Scoville & Solomon1975, Jackson et al. 2006 ). However, in the Galaxy, it is very difficult to distinguishbetween a spiral and ring, most recent investigations seem to favor the idea that thisstructure is a spiral arm, c.f Jackson et al. (2008) or Dobbs & Burkert (2012). Anotherstructure that might plausibly be visible as a star-forming ring to an outside observeris the Near/Far Three-Kiloparsec Arm (van Woerden, Rougoor, & Oort 1957, Dame& Thaddeus 2008). Simulations of gas flow in a gravitational potential consistentwith the Galactic bar (Bissantz et al. 2003, Englmaier & Gerhard 1999, Fux 1999)predict that these two structures should form an oval around the bar. Although earlysearches of this structure showed no evidence for star formation (Lockman 1980), recentsurveys of class II methanol masers and HII regions indicate a significant amount ofmassive star formation (Green et al 2009, Anderson et al 2014). An excess of OH/IRstars (Sevenster 1999) and enhanced near-infrared star counts of bright stars, mK < 9,(Lopez-Corredoira et al. 2001) have been noted at l = 338. Both authors noted thecoincidence of this direction with the tangency direction of the Near Three-Kiloparsecarm and suggested that this might be part of a ring, even before the discovery of theFar Three Kiloparsec Arm! I will review what is known about interstellar and stellarstructure of the Near and Far Three Kiloparsec Arms and discuss what further workshould be done to resolve whether this structure truly is a ring.

A Ring-like Stellar Overdensity Structure in the LargeMagellanic Cloud 31

May14:5020 min

Yumi Choi1, David Nidever2, Knut Olsen2, Gurtina Besla1, Robert Blum2, CliffJohnson3, Dennis Zaritsky1 and the SMASH team

1University of Arizona; 2NOAO; 3Northwestern University; SMASH team

We explore stellar number density structures in the southern disk of the Large Magel-lanic Cloud (LMC) and detect a ring-like stellar overdensity at around 5 kpc from theLMC center. This structure does not have any symmetric counterpart in the northerndisk, but very similar structures can be seen in numerical simulations of the interactionof the Magellanic Clouds with each other. We find that the stellar populations associ-ated with the overdensity are intermediate age which is consistent with an increase inthe star formation rate at 3.5 Gyr ago in both galaxies. This suggests that the LMC

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overdensity structure is likely a product of the tidal interaction with SMC and not withthe Milky Way.

Unravelling the Origin of the Monoceros Ring - Detailedabundances in the Southern Structure 31

May15:1020 min

Thomas Bensby

Lund Observatory

The Milky Way outer disk contains a plethora of stellar overdensities and structuresthat we currently do not know the origin of. For instance, the largest structure, theMonoceros Ring, has since its discovery more than 10 years ago been attributed toan accreted dwarf galaxy, the warp of the Milky Way disk, or just the Milky Wayspiral arms. However, the SDSS and PANSTARRS1 surveys now show indicationsthat the Monoceros Ring could be ripples in the disk, caused by a dwarf galaxy thatplunged through the disk. Using VLT and the FLAMES multifibre spectrograph wehave obtained high-resolution spectra to determine detailed elemental abundances andstellar ages for stars in the Monoceros structures to see if they differ from the MilkyWay field stars. This allows us to put constraints on the nature of the Monoceros Ringstars and if they are of Galactic or extra-galactic origin.

Session XIV - Secular Processes in Disk Galaxies

Spiral arms, the warp & the stream in M33 as a re-sult of an interaction with M31 31

May16:0015 min

Marcin Semczuk1, Ewa L. Lokas1, Jean-Baptiste Salomon1, E. Athanassoula2, ElenaD’Onghia3

1Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences; 2Laboratoired’Astrophysique de Marseille; 3University of Wisconsin-Madison

The Triangulum Galaxy (M33) possesses several morphological traits suggesting itspast interaction with the Andromeda Galaxy (M31). These are: the gaseous warp, itsstellar counterpart called the stream and the predominant 2-armed spiral structure. Inaddition to the morphology of M33, a peak has been found in star formation histories ofboth galaxies 2 Gyr ago. We present results of N-body/SPH simulations of the recentinteraction between M33 and M31 in which these features of M33 are qualitativelyreproduced. In our simulations M33 is modeled as a gaseous and stellar disk embeddedin a dark matter halo. The potential of M31 is approximated with a live dark matter

40


halo. M33 is passing M31 on an orbit with a pericenter distance of 37 kpc and itsrelative velocity at the end of the simulation is consistent with the estimates of propermotions of both M33 and M31 known from the literature. Tidal forces from M31 inducethe gaseous warp, the stellar stream and grand-design spiral arms in M33 during thepericenter passage. These features survive until the present time and have similarshapes as the observed ones. We also find that tidal forces were sufficent to compressthe gas in M33 and trigger a star formation burst at radii similar to where it is observed.

Black Hole Mass Scaling Relations for Spiral GalaxiesDetermined from Pitch Angles and Multicomponent

Structural Decompositions 31May16:1520 min

Benjamin Lee Davis1, Alister Graham1, Marc Seigar2, Ewan Cameron3

1Centre for Astrophysics and Supercomputing, Swinburne University of Technology;2University of Minnesota Duluth; 3University of Oxford

In an effort to derive accurate bulge magnitudes for the current full sample of 43 spiralgalaxies with directly measured supermassive black hole masses, we have analyzed theirimages and light profiles in exquisite detail. We found that it was important to accountfor not just the bars, but also the rings and partial rings, i.e. ansae, at the ends of thesebars. We have additionally performed a careful measurement of the spiral-arm pitchangles for these galaxies. This has enabled us to revise the black hole scaling relationsfor spiral galaxies, using more accurate measurements than ever before, and with asample size which is double that of previous works. While presenting this work, I willdiscuss ideas about the AGN-galaxy (feedback) connection, the efficacy of these scalingrelations for predicting black hole masses including intermediate-mass black holes ingalaxies with X-ray AGN and implications for the longevity of bars.

Black Hole Growth in Disk Galaxies Mediated by the SecularEvolution of Short Bars 31

May16:3520 min

Min Du1, Victor P. Debattista2, Juntai Shen3, Luis C. Ho1,Peter Erwin4

1Kavli Institute for Astronomy and Astrophysics, Peking University, China; 2JeremiahHorrocks Institute, University of Central Lancashire, UK; 3Key Laboratory of Research inGalaxies and Cosmology, Shanghai Astronomical Observatory, China; 4Max-Planck-Insitut

fur extraterrestrische Physik, Garching, Germany

In a series of papers (Du et al. 2015, 2016, 2017a), we have developed realistic ”barswithin bars” (S2B) systems using N-body simulations. The short bars of sub-kiloparsecradius have been hypothesized to be an important mechanism for driving gas inflowsefficiently to small scale, feeding central BHs in the secular evolution. The growth of

41


black holes (BHs) in disk galaxies lacking classical bulges, which implies an absenceof significant mergers, appears to be driven by such secular processes. We quantifythe maximum BH mass allowed by this mechanism with our numerical S2B models(Du et al. 2017b). We find that short bars can be destroyed quickly when BHs ofmass Mbh 0.05%-0.2% of the total stellar mass (M*) are present. Thus, the dissolutionof short inner bars is possible, perhaps even frequent, in the universe. An importantimplication of this result is that inner-bar-driven gas inflows may be terminated whenBHs grow to 0.1%M* . We predict that 0.2%M* is the maximum mass of BHs allowedif they are fed predominately via inner bars. This value matches well the maximumratio of BH-to-host-galaxy stellar mass observed in galaxies with pseudo-bulges andmost nearby active galactic nucleus host galaxies. This hypothesis provides a novelexplanation for the lower Mbh/M* in galaxies that have avoided significant mergerscompared with galaxies with classical bulges.

A combined photometric and kinematic recipe for evaluatingthe nature of bulges using the CALIFA sample 31

May16:5515 min

Justus Neumann1, L. Wisotzki1, O. Choudhury1, D. Gadotti2, C.J. Walcher1, J.Bland-Hawthorn3, R. Garcia-Benito4, R.M. Gonzales-Delgado4, B. Husemann5, R.A.

Marino6, I. Marquinez5, S.F. Sanchez7, B. Ziegler8 and CALIFA collaboration1Leibniz-Institut for Astrophysik Potsdam (AIP); 2European Southern Observatory (ESO);

3University of Sydney; 4Instituto de Astrofisica de Andalucia; 5Max-Planck-InstitutHeidelberg; 6ETH Zurich; 7Universidad Nacional Autonoma de Mexico; 8University of

Vienna; CALIFA collaboration

Understanding the nature of bulges in disc galaxies can provide important insights intothe formation and evolution of galaxies and their secular structures. For instance, thepresence of a classical bulge suggests a relatively violent history, in contrast, the presenceof simply an inner disc (also referred to as “pseudobulge”) indicates the occurrence ofsecular evolution processes in the main disc. However, we still lack criteria to effectivelycategorize bulges, limiting our ability to study their impact on the evolution of the hostgalaxies and their secularily built structures. In this talk, I will present a recipe toseparate inner discs from classical bulges by combining four different parameters fromphotometric and kinematic analyses. I will also show the results of applying that recipeto a sample of 45 galaxies from the integral-field spectroscopic survey CALIFA. To aidin categorizing bulges within these galaxies, we performed 2D image decomposition todetermine bulge Sersic index, bulge-to-disc light ratio, surface brightness and effectiveradius and we used growth curve analysis to derive a new concentration index, C20,50.We further extracted the stellar kinematics from CALIFA data cubes and analyzedthe radial velocity dispersion profile. The results of the different approaches are ingood agreement and allow a safe classification for approximately 95% of the galaxies.In particular, we found that our new concentration index performs better than thetraditionally used C50,90 when yielding the nature of bulges. We also found that a

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combined use of this index and the Kormendy relation gives a robust indication of thephysical nature of the bulge.

The Dust Forecast, Predicting the Dust Attenuation in SpiralDisk Galaxies 31

May17:1020 min

Benne Willem Holwerda1, Bill Keel2, and the Galaxy Zoo team1University of Louisville; 2The University of Alabama

Interstellar dust is still a dominant uncertainty in Astronomy, limiting precision in e.g.,cosmological distance estimates and models of how light is re-processed within a galaxy.When a foreground galaxy serendipitously overlaps a more distant one, the latter back-lights the dusty structures in the nearer foreground galaxy. Such an overlapping orocculting galaxy pair can be used to measure the distribution of dust in the closestgalaxy with great accuracy. The STARSMOG program uses Hubble to map the dis-tribution of dust in foreground galaxies in fine (<100 pc) detail. Integral Field Unit(IFU) observations will map the effective extinction curve, disentangling the role offine-scale geometry and grain composition on the path of light through a galaxy. Theoverlapping galaxy technique promises to deliver a clear understanding of the dust ingalaxies: geometry, a probability function of dimming as a function of galaxy mass andradius, and its dependence on wavelength.

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Friday, June 1, 2018

Session XV - Rings and other Galaxy Structure in

Simulations

Ring galaxies in the nearby and distant Universe 01June09:0040 min

Frederic Bournaud

CEA Saclay, France

A large number of ring galaxies are observed in the nearby Universe, but also in high-redshift surveys such as the Hubble UDF, CANDELS, etc. Rings can form by severalmechanisms: galaxy collisions and interactions, resonances in barred galaxies, internalinstabilities. I propose to review the expected signatures of formation mechanisms,based both on observations of nearby ring galaxies and hydrodynamic simulations, andcompared to the observed properties of ring galaxies at high redshift.

Warps, waves and rings in the stellar discs of Aurigacosmological simulations 01

June09:4020 min

Facundo Ariel Gomez1, Simon D.M. White2, Robert J.J. Grand3, F. Marinacci4,V.Springel3, R. Pakmor3

1University of La Serena; 2Max Planck Institute fur Astrophysics; 3Heidelberger Institut furTheoretische Studien; 4Massachusetts Institute of Technology

During this talk I will present an overview of our recent work which aims to characterizethe impact of host-satellite interactions on the observable properties of Milky Way-likegalaxies. We use a suite of fully cosmological high resolutions simulations from theAuriga Project to analyze the present-day vertical structure of individual Milky Way-sized models. At redshift zero, about 70% of our galactic discs show strong verticalpatterns, with amplitudes that can exceed 2 kpc. Half of these are typical ‘integral sign’warps. The rest are corrugation patterns, similar to those observed in the Milky Way.The associated mean vertical motions can be as large as 30 km/s. These perturbationshave a variety of causes such as close encounters with satellites or accretion of misalignedcold gas from halo infall or from mergers. More interestingly, I will show examplesof how the halo dark matter component can react to distant fly-by interactions bydeveloping overdensity wakes. These responses can induce strong perturbations on agalactic disc, such as warps and lopsidedness and ringing, that can be used to studyunseen structure in the outskirt of galaxies.

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Galactic bars and galaxy interactions in the Illustrissimulation 01

June10:0020 min

Nicolas Peschken

Nicolaus Copernicus Astronomical Center, Warsaw, Poland

Central galactic bars have been found to be very common in late-type galaxies, beingobserved in about 60-70 % of local disc galaxies. Their formation mechanisms are di-verse, as they can form in secular evolution, or be triggered by external perturbers. Ipropose to present my current work about how bars form and evolve in a cosmologicalcontext, in particular when the disc galaxy hosting the bar is interacting with othergalaxies. To do this, I use the Illustris simulation, which is a large hydrodynamicalcosmological simulation based on the moving mesh code AREPO, reproducing manyobservational results in the area of galaxy formation and evolution. I examine the prop-erties of bars in Illustris disc galaxies at different redshifts, their formation mechanism,and the evolution of the bar fraction with time, stellar mass and gas content. Further-more, I investigate how bars can be formed by tidal forces from galaxy interactions suchas flybys, and how the characteristics of the newly formed bar depend on the nature ofthe interaction. In the case of a pre-existing bar, galaxy interactions can reinforce it,weaken it or even destroy it. Those cases can be studied by deriving the bar strengthover time, and looking at the effect of interactions on its evolution. For a flyby, the baris affected differently depending on how strong the interaction is, and whether the orbitof the encounter is prograde or retrograde with respect to the bar rotation (Peschken& Lokas, to be submitted soon).

Tidally induced bars in gas-rich dwarf galaxies orbiting theMilky Way 01

June10:2015 min

Grzegorz Gajda1, Ewa L. Lokas1, Lia Athanassoula3

1Nicolaus Copernicus Astronomical Center, Poland; 2Laboratoire d’Astrophysique deMarseille

In the Local Group of galaxies we can distinguish two categories of dwarf galaxies.Those which are far away from the Milky Way and Andromeda are predominantlyclassified as dwarf irregulars (dIrr), while the ones which are close to them are labelledas dwarf spheroidals (dSph). The dIrr galaxies exhibit certain degree of rotation andcontain gas, whereas the dSph galaxies have spheroidal shapes supported by randommotions of stars and are devoid of gas. The spatial separation of the two groups pointsto a possible evolutionary relation between them. In the tidal stirring scenario initiallydisky dwarf galaxies are transformed into spheroids due to repeated tidal interactionswith the host galaxy. An intermediate stage of this process involves the formation ofa tidally induced bar in the stellar disc of the dwarf. I will present results of two N-body+SPH simulations following the evolution of a gas-rich dwarf galaxy orbiting in a

45


potential resembling a Milky Way-like host. In the two runs two different gas fractionwere used and the result will be compared to a pure N-body simulation. In all cases,bars form in the stellar component during the first pericenter passage, while the gaseouscomponent remains approximately axisymmetric. The bars in the hydro runs are onlyslightly weaker and have similar lengths compared to the collisionless case. After theformation, the bars are stable and steadily rotating until the second pericenter passage.The further evolution depends on the gas fraction. In the runs with little or no gas thebars survive until the end, however the exact outcome of further encounters with thehost depend on the exact position angle of the bar during the interaction. Dependingon the relative orientation of the bar with respect to the direction to the host, the barmay be spun up and weakened or spun down and strengthened. In the gas-rich dwarfthe bar is weakened at the second pericenter and practically disappears afterwards.During the simulations the discs thicken and lose a significant part of their rotation.The results presented here may be useful for modeling satellites of the Milky Way, suchas Sagittarius, Ursa Minor and Carina, whose elongated shapes can be explained bythe existence of a bar.

Bar formation in cosmological simulations 01June10:3515 min

Tommaso Zana1, Massimo Dotti2, Francesco Haardt1, Pedro R. Capelo3, LucioMayer3, Silvia Bonoli4

1University of Insubria; 2University of Milano-Bicocca; 3University of Zurich; 4CEFCA

I will detail the physical processes behind the formation and growth of the galacticbar in a fully cosmological context, including the possible effect of the most recentdynamical events (minor mergers and flybys after redshift 1). I will present the analysisof the Eris-BH and Eris-2k runs (Bonoli et al. 2016, Sokowlowska et al. 2016), two highresolution zoom-in cosmological simulation which result in the formation of two slightlydifferent Milky way like barred galaxy. I will show that the tidal interactions analyzedplay a minor role in the formation process, but their influence, in general, work againstthe coherent growth of the structures.

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Session XVI - Secular Structures in a Cosmological

Context

Galaxy Morphology from Galaxy Zoo 01June11:1540 min

Karen L Masters

Haverford College

The Galaxy Zoo project (www.galaxyzoo.org) has provided quantitative visual mor-phologies for over a million galaxies (including the entire Sloan Digital Sky Surveys,or SDSS Main Galaxy Sample, all public HST surveys, UKIDSS, GAMA and mostrecently the Illustris Simulation), and has been part of a reinvigoration of interest inthe morphologies of galaxies and what they reveal about the evolution of galaxies. Themorphological information collected by Galaxy Zoo has shown itself to be a powerfuldatabase for studying galaxy evolution, and Galaxy Zoo continues to collect classifica-tions - currently serving imaging from DECaLS. I will review how to make best use ofthe morphologies from Galaxy Zoo, and highlight some of the results from the last 10years of the project. I will also look forward to future plans and projects in the GalaxyZoo family.

Redshift evolution of bars, rings and spiral arms 30May11:5525 min

Preethi Nair


Understanding the physical processes responsible for the growth of galaxies is one ofthe key challenges in extragalactic astronomy. The assembly history of a galaxy isimprinted in its detailed morphology. The bulge-to-total ratio of galaxies, the presenceor absence of bars, rings, spiral arms, etc, all have implications for the past merger,star formation, and feedback history of a galaxy. Here, I present a visually classifiedcatalog of bars and rings from the HST COSMOS Survey. Using this sample and myvisually classified sample from SDSS, I will present results on the evolution of the barand ring fractions since z∼1 and the impact of bars/rings on the evolution of SFR indisk galaxies over the last 6 billion years.

Session XVII - Discussion and Concluding Remarks

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Author Index

Aguerri, 9Athanassoula, 12

Benjamin, 39Bensby, 40Bittner, 27Bournaud, 44Buta, 10, 16Byrd, 26

Choi, 39Combes, 17

D’Onghia, 34Dıaz-Garcıa, 20Daniel, 30Davis, 41de Lorenzo-Caceres, 33Domingue, 17Donohoe-Keyes, 32Du, 41

Erwin, 11

Font, 30Forbes, 14Fragkoudi, 22, 25Fraser-McKelvie, 32Freeman, 9Fuentes-Carrera, 14

Gadotti, 19Gajda, 45Garma, 31Gomez, 44

Hancock, 27Higdon, 37Holwerda, 43

Jogee, 31

Jones, 26

Katkov, 23Keel, 15, 34Knapen, 17Kostiuk, 18

Laurikainen, 24

Maksym, 19Masters, 47Mendez-Abreu, 11Moiseev, 37

Nair, 47Neumann, 25, 42

Perez, 24Peschken, 45Peterken, 36Peters, 33Pfenniger, 13

Renaud, 38Romero-Gomez, 12

Sanchez Gil, 35Salo, 10Seidel, 15, 21Semczuk, 40Seo, 23Shen, 38Sil’chenko, 18Simon, 20Sormani, 22

Talei, 16

Zana, 46Zhang, 29

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Notes

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Documents

Galactic Rings Signposts of Secular Evolution in Disk Galaxies · Galactic Rings Signposts of Secular Evolution in Disk Galaxies 27th May, 2018 { 1st June, 2018 The University of